This commit adds two new tests. One checks that a symbol in the current
project gets priority over a symbol in the standard library. Another
checks that a symbol in a third party dependency gets priority over a
symbol in the standard library. We don't get either of these right
today.
Note that these comparisons are done ceteris paribus. A symbol from the
standard library could still be ranked above a symbol elsewhere.
(Although I believe currently this is somewhat rare.)
2196ef3a33