file_finder: Respect .gitignore and file_scan_inclusions with ** in glob (#40654)

Closes #39037 

Previously, the code split the `**/.env` glob in `file_scan_inclusions`
into two sources for the `PathMatcher`: `["**", "**/.env"]`. This
approach works for directories, but including `**` will match all
directories and their files. To address this, I now select the
appropriate `PathMatcher` using only `**/.env` when specifically
targeting a file to determine whether to include it in the file finder.

Release Notes:

- Fixed: respect `.gitignore` and `file_scan_inclusions` settings with
`**` in glob for file finder

---------

Signed-off-by: Benjamin <5719034+bnjjj@users.noreply.github.com>
Co-authored-by: Julia Ryan <juliaryan3.14@gmail.com>

crates/worktree/src/worktree_tests.rs

@@ -760,6 +760,7 @@ async fn test_file_scan_inclusions(cx: &mut TestAppContext) {
             "prettier": {
                 "package.json": "{}",
             },
+            "package.json": "//package.json"
         },
         "src": {
             ".DS_Store": "",