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

lib/amigaos.h

@@ -39,4 +39,3 @@ void Curl_amiga_cleanup(void);
 #endif
 
 #endif /* HEADER_CURL_AMIGAOS_H */
-

lib/cfilters.c

@@ -646,4 +646,3 @@ size_t Curl_conn_get_max_concurrent(struct Curl_easy *data,
                               &n, NULL) : CURLE_UNKNOWN_OPTION;
   return (result || n <= 0)? 1 : (size_t)n;
 }
-

lib/connect.c

@@ -1446,4 +1446,3 @@ CURLcode Curl_conn_setup(struct Curl_easy *data,
 out:
   return result;
 }
-

lib/sendf.c

@@ -421,4 +421,3 @@ CURLcode Curl_read(struct Curl_easy *data,   /* transfer */
 out:
   return result;
 }
-