Split js library tests out of test_other.py into their own file. NFC (emscripten-core#25603)

The `test_other.py` is over 15,000 lines long so its to to carve out
larger subsections where possible.

The tests themselves are all unmodified aside from one that was
referring to filenames that got moved.

Author: sbc100

.circleci/config.yml

@@ -1,5 +1,6 @@
 version: 2.1
 
+
 orbs:
   win: circleci/[email protected]
 
@@ -1057,7 +1058,7 @@ jobs:
       - run-tests-linux:
           # some native-dependent tests fail because of the lack of native
           # headers on emsdk-bundled clang
-          test_targets: "other skip:other.test_native_link_error_message"
+          test_targets: "other jslib skip:other.test_native_link_error_message"
   test-browser-chrome:
     executor: focal
     environment: