tests: change Python code style to pass ruff checks

Most of the changes consisted of removing unused imports and unnecessary
f-strings.

pytest: fixes for recent python, add FTP tests

Fixes:
- in uds tests, abort also silently on os errors
- be conservative on the h3 goaway duration
- detect curl debug build and u

pytest: fixes for recent python, add FTP tests

Fixes:
- in uds tests, abort also silently on os errors
- be conservative on the h3 goaway duration
- detect curl debug build and use in checks
- fix caddy version check for slight difference under linux
- set caddy default path fitting for linux
- fix deprecation warnings in valid time checks

FTP tests:
- add '--with-test-vsftpd=path' to configure
- use vsftpd default path suitable for linux
- add test_30 with plain FTP tests
- add test_31 with --ssl-reqd FTP tests
- add vsftpd to linux GHA for pytest workflows

Closes #13661

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pytest: Scorecard tracking CPU and RSS

Closes #12765

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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proxy: http2 proxy tunnel implementation

- currently only on debug build and when env variable
CURL_PROXY_TUNNEL_H2 is present.
- will ALPN negotiate with the proxy server and swit

proxy: http2 proxy tunnel implementation

- currently only on debug build and when env variable
CURL_PROXY_TUNNEL_H2 is present.
- will ALPN negotiate with the proxy server and switch
tunnel filter based on the protocol negotiated.
- http/1.1 tunnel code moved into cf-h1-proxy.[ch]
- http/2 tunnel code implemented in cf-h2-proxy.[ch]
- tunnel start and ALPN set remains in http_proxy.c
- moving all haproxy related code into cf-haproxy.[ch]

VTLS changes
- SSL filters rely solely on the "alpn" specification they
are created with and no longer check conn->bits.tls_enable_alpn.
- checks on which ALPN specification to use (or none at all) are
done in vtls.c when creating the filter.

Testing
- added a nghttpx forward proxy to the pytest setup that
speaks HTTP/2 and forwards all requests to the Apache httpd
forward proxy server.
- extending test coverage in test_10 cases
- adding proxy tests for direct/tunnel h1/h2 use of basic auth.
- adding test for http/1.1 and h2 proxy tunneling to pytest

Closes #10780

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tests/http: remove year ranges from copyrights

Closes #10763

tests: rename tests/tests-httpd to tests/http

- httpd is only one server we test with
- the suite coveres the HTTP protocol in general where
the default test cases need a more b

tests: rename tests/tests-httpd to tests/http

- httpd is only one server we test with
- the suite coveres the HTTP protocol in general where
the default test cases need a more beefy environment

Closes #10654

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