Rename custom-typeshed-dir, target-version and current-directory CLI options (#14930)

## Summary

This PR renames the `--custom-typeshed-dir`, `target-version`, and
`--current-directory` cli options to `--typeshed`,
`--python-version`, and `--project` as discussed in the CLI proposal
document.
I added aliases for `--target-version` (for Ruff compat) and
`--custom-typeshed-dir` (for Alex)

## Test Plan

Long help

```
An extremely fast Python type checker.

Usage: red_knot [OPTIONS] [COMMAND]

Commands:
  server  Start the language server
  help    Print this message or the help of the given subcommand(s)

Options:
      --project <PROJECT>
          Run the command within the given project directory.
          
          All `pyproject.toml` files will be discovered by walking up the directory tree from the project root, as will the project's virtual environment (`.venv`).
          
          Other command-line arguments (such as relative paths) will be resolved relative to the current working directory."#,

      --venv-path <PATH>
          Path to the virtual environment the project uses.
          
          If provided, red-knot will use the `site-packages` directory of this virtual environment to resolve type information for the project's third-party dependencies.

      --typeshed-path <PATH>
          Custom directory to use for stdlib typeshed stubs

      --extra-search-path <PATH>
          Additional path to use as a module-resolution source (can be passed multiple times)

      --python-version <VERSION>
          Python version to assume when resolving types
          
          [possible values: 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13]

  -v, --verbose...
          Use verbose output (or `-vv` and `-vvv` for more verbose output)

  -W, --watch
          Run in watch mode by re-running whenever files change

  -h, --help
          Print help (see a summary with '-h')

  -V, --version
          Print version
```

Short help 

```
An extremely fast Python type checker.

Usage: red_knot [OPTIONS] [COMMAND]

Commands:
  server  Start the language server
  help    Print this message or the help of the given subcommand(s)

Options:
      --project <PROJECT>         Run the command within the given project directory
      --venv-path <PATH>          Path to the virtual environment the project uses
      --typeshed-path <PATH>      Custom directory to use for stdlib typeshed stubs
      --extra-search-path <PATH>  Additional path to use as a module-resolution source (can be passed multiple times)
      --python-version <VERSION>  Python version to assume when resolving types [possible values: 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13]
  -v, --verbose...                Use verbose output (or `-vv` and `-vvv` for more verbose output)
  -W, --watch                     Run in watch mode by re-running whenever files change
  -h, --help                      Print help (see more with '--help')
  -V, --version                   Print version

```

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

crates/red_knot_python_semantic/src/program.rs

@@ -10,7 +10,7 @@ use crate::Db;
 
 #[salsa::input(singleton)]
 pub struct Program {
-    pub target_version: PythonVersion,
+    pub python_version: PythonVersion,
 
     #[return_ref]
     pub(crate) search_paths: SearchPaths,
@@ -19,16 +19,16 @@ pub struct Program {
 impl Program {
     pub fn from_settings(db: &dyn Db, settings: &ProgramSettings) -> anyhow::Result<Self> {
         let ProgramSettings {
-            target_version,
+            python_version,
             search_paths,
         } = settings;
 
-        tracing::info!("Target version: Python {target_version}");
+        tracing::info!("Python version: Python {python_version}");
 
         let search_paths = SearchPaths::from_settings(db, search_paths)
             .with_context(|| "Invalid search path settings")?;
 
-        Ok(Program::builder(settings.target_version, search_paths)
+        Ok(Program::builder(settings.python_version, search_paths)
             .durability(Durability::HIGH)
             .new(db))
     }
@@ -56,7 +56,7 @@ impl Program {
 #[derive(Clone, Debug, Eq, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize))]
 pub struct ProgramSettings {
-    pub target_version: PythonVersion,
+    pub python_version: PythonVersion,
     pub search_paths: SearchPathSettings,
 }
 
@@ -75,7 +75,7 @@ pub struct SearchPathSettings {
     /// Optional path to a "custom typeshed" directory on disk for us to use for standard-library types.
     /// If this is not provided, we will fallback to our vendored typeshed stubs for the stdlib,
     /// bundled as a zip file in the binary
-    pub custom_typeshed: Option<SystemPathBuf>,
+    pub typeshed: Option<SystemPathBuf>,
 
     /// The path to the user's `site-packages` directory, where third-party packages from ``PyPI`` are installed.
     pub site_packages: SitePackages,
@@ -86,7 +86,7 @@ impl SearchPathSettings {
         Self {
             src_root,
             extra_paths: vec![],
-            custom_typeshed: None,
+            typeshed: None,
             site_packages: SitePackages::Known(vec![]),
         }
     }