tidy-up: mostly whitespace nits

- delete completed TODO from `./CMakeLists.txt`.
- convert a C++ comment to C89 in `./CMake/CurlTests.c`.
- delete duplicate EOLs from EOF.
- add missing EOL at EOF.
- delete whitespace at EOL (except from expected test results).
- convert tabs to spaces.
- convert CRLF EOLs to LF in GHA yaml.
- text casing fixes in `./CMakeLists.txt`.
- fix a codespell typo in `packages/OS400/initscript.sh`.

Closes #11772

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -31,9 +31,9 @@ body:
     id: expected-behaviour
     attributes:
       label: I expected the following
-    validations: 
+    validations:
       required: false
-  
+
   - type: textarea
     id: version
     attributes: