build: tidy-up MSVC CRT warning suppression macros

build: tidy-up MSVC CRT warning suppression macros

- curl_setup.h: replace `_CRT_SECURE_NO_DEPRECATE` with
  `_CRT_SECURE_NO_WARNINGS`, which seems to be the preferred,
  more recent macro for this. Also syncing with libssh2.
  They are equivalent for curl sources with the supported compilers.
- cmake: stop setting `_CRT_SECURE_NO_DEPRECATE` globally for examples.
- examples: suppress CRT deprecation warnings on a per-file basis.
  To make it work when compiling examples out of curl's build systems.
  Use `_CRT_SECURE_NO_WARNINGS`.
- examples: document the functions requiring `_CRT_SECURE_NO_WARNINGS`.
- examples/block_ip: delete superfluous `_CRT_SECURE_NO_WARNINGS`.
- examples/block_ip: limit `_CRT_NONSTDC_NO_DEPRECATE` to MSVC.
- examples/log_failed_transfers: fix to set `_CRT_SECURE_NO_WARNINGS`
  before headers and limit to MSVC.
- curl_setup.h: document which SDKs support `_CRT_NONSTDC_NO_DEPRECATE`.

Closes #19175