winbuild: MS-DOS batch tidy-ups

- prefer `.bat` extension over `.cmd` for MS-DOS batch, which also
avoids confusion with OS/400 `.cmd` files.
- cleanup `echo` quotes, drop them con

winbuild: MS-DOS batch tidy-ups

- prefer `.bat` extension over `.cmd` for MS-DOS batch, which also
avoids confusion with OS/400 `.cmd` files.
- cleanup `echo` quotes, drop them consistently.
- delete empty output line from one of the error branches.
- prefer lowercase commands like the rest of MS-DOS batches.
- delete a contraction.
- drop backticks from error message.
- use `nmake.exe` consistently.
- use equal/not-equal operator style consistently.
- inline a single-line `if` branch.
- delete exceptions and rules dealing with Windows `.cmd` extension.

Closes #14084

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CI: add whitespace checker

Fix issues detected.

Also:

- One of the `.vc` files used LF EOLs, while the other didn't.
Make that one also use LF EOLs, as this is appare

CI: add whitespace checker

Fix issues detected.

Also:

- One of the `.vc` files used LF EOLs, while the other didn't.
Make that one also use LF EOLs, as this is apparently supported by
`nmake`.

- Drop `.dsw` and `.btn` types from `.gitattributes`.
The repository doesn't use them.

- Sync section order with the rest of files in
`tests/certs/EdelCurlRoot-ca.prm`.

- Indent/align `.prm` and `.pem` files.

- Delete dummy `[something]` section from `.prm` and `.pem` files.

Mental note:
MSVC `.sln` files seem to accept spaces for indentation and also support
LF line-endings. I cannot test this and I don't know what's more
convenient when updating them, so left them as-is, with specific
exclusions.

Closes #14031

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