build: enable missing OpenSSF-recommended warnings, with fixes

https://best.openssf.org/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++.html
as of 2023-11-29 [1]

build: enable missing OpenSSF-recommended warnings, with fixes

https://best.openssf.org/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++.html
as of 2023-11-29 [1].

Enable new recommended warnings (except `-Wsign-conversion`):

- enable `-Wformat=2` for clang (in both cmake and autotools).
- add `CURL_PRINTF()` internal attribute and mark functions accepting
printf arguments with it. This is a copy of existing
`CURL_TEMP_PRINTF()` but using `__printf__` to make it compatible
with redefinting the `printf` symbol:
https://gcc.gnu.org/onlinedocs/gcc-3.0.4/gcc_5.html#SEC94
- fix `CURL_PRINTF()` and existing `CURL_TEMP_PRINTF()` for
mingw-w64 and enable it on this platform.
- enable `-Wimplicit-fallthrough`.
- enable `-Wtrampolines`.
- add `-Wsign-conversion` commented with a FIXME.
- cmake: enable `-pedantic-errors` the way we do it with autotools.
Follow-up to d5c0351055d5709da8f3e16c91348092fdb481aa #2747
- lib/curl_trc.h: use `CURL_FORMAT()`, this also fixes it to enable format
checks. Previously it was always disabled due to the internal `printf`
macro.

Fix them:

- fix bug where an `set_ipv6_v6only()` call was missed in builds with
`--disable-verbose` / `CURL_DISABLE_VERBOSE_STRINGS=ON`.
- add internal `FALLTHROUGH()` macro.
- replace obsolete fall-through comments with `FALLTHROUGH()`.
- fix fallthrough markups: Delete redundant ones (showing up as
warnings in most cases). Add missing ones. Fix indentation.
- silence `-Wformat-nonliteral` warnings with llvm/clang.
- fix one `-Wformat-nonliteral` warning.
- fix new `-Wformat` and `-Wformat-security` warnings.
- fix `CURL_FORMAT_SOCKET_T` value for mingw-w64. Also move its
definition to `lib/curl_setup.h` allowing use in `tests/server`.
- lib: fix two wrongly passed string arguments in log outputs.
Co-authored-by: Jay Satiro
- fix new `-Wformat` warnings on mingw-w64.

[1] https://github.com/ossf/wg-best-practices-os-developers/blob/56c0fde3895bfc55c8a973ef49a2572c507b2ae1/docs/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C%2B%2B.md

Closes #12489

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tests/http: make curl_setup.h the first include

This is required for the macros there to take effect for system
libraries. Specifically, including the system libraries first led to
w

tests/http: make curl_setup.h the first include

This is required for the macros there to take effect for system
libraries. Specifically, including the system libraries first led to
warnings about `_FILE_OFFSET_BITS` being redefined in curl_config.h on
the Solaris autobuilds for ws-data.c and ws-pingpong.c.
Also make the curl includes come first for the other source files here
for consistency.

Closes https://github.com/curl/curl/pull/11046

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tests/http: more tests with specific clients

- Makefile support for building test specific clients in tests/http/clients
- auto-make of clients when invoking pytest
- added test_09_0

tests/http: more tests with specific clients

- Makefile support for building test specific clients in tests/http/clients
- auto-make of clients when invoking pytest
- added test_09_02 for server PUSH_PROMISEs using clients/h2-serverpush
- added test_02_21 for lib based downloads and pausing/unpausing transfers

curl url parser:
- added internal method `curl_url_set_authority()` for setting the
authority part of a url (used for PUSH_PROMISE)

http2:
- made logging of PUSH_PROMISE handling nicer

Placing python test requirements in requirements.txt files
- separate files to base test suite and http tests since use
and module lists differ
- using the files in the gh workflows

websocket test cases, fixes for we and bufq
- bufq: account for spare chunks in space calculation
- bufq: reset chunks that are skipped empty
- ws: correctly encode frames with 126 bytes payload
- ws: update frame meta information on first call of collect
callback that fills user buffer
- test client ws-data: some test/reporting improvements

Closes #11006

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