Code fixes adding carriage returns to LF documents

Code fixes are generating files with mixed LF and CRLF line endings. See:
* `codeFixAddMissingMember5`
* `codeFixAddMissingMember7`
* `codeFixSuperAfterThis`
* `codeFixSuperCall`
* `importNameCodeFix*` (see comment in `fourslash.ts` tagged `GH#18445`)