zeta: Add zlib to license detection + ignore symbol differences (#37238)

See discussion on #36564. Makes the license regexes a less fragile by
not matching on symbols, while also excluding cases where a long file
ends with a valid license. Also adds Zlib license, a commented out test
to check all license-like files discovered in the homedir, and more
testcases.

Not too happy with the efficiency here, on my quite good computer it
takes ~120ms to compile the regex and allocates ~8mb for it. This is
just not a great use of regexes, I think something using eager substring
matching would be much more efficient - hoping to followup with that.

Release Notes:

- Edit Prediction: Added Zlib license to open-source licenses eligible
for data collection.

Cargo.lock

@@ -20817,6 +20817,7 @@ dependencies = [
  "gpui",
  "http_client",
  "indoc",
+ "itertools 0.14.0",
  "language",
  "language_model",
  "log",