build: do not apply curl debug macros to tests/server by default

It seems unnecessary and possibly unexpected to build test servers with
debug-enabled features and memory tracking whenever the tested curl is
built like that (which is a requirement for some tests, so curl is
mostly built like that when running tests.) It also makes building
servers a little bit faster with cmake for the most common cases.

You can apply debug options to `tests/server` with these new options:
- `./configure`: `--enable-server-debug`.
- cmake: `-DENABLE_SERVER_DEBUG`.

Also sync the way we pass these macros in autotools, with CMake builds.
Before this patch, autotools passed them via `curl_config.h`. After this
patch it passes them on the command-line, like cmake builds do.

This patch also make these option no longer passed to examples and
`http/client` in cmake builds, where they were no-ops anyway.

Ref: #15000
Closes #16705

docs/INSTALL-CMAKE.md

@@ -245,6 +245,7 @@ target_link_libraries(my_target PRIVATE CURL::libcurl)
 - `ENABLE_CURLDEBUG`:                       Enable TrackMemory debug feature. Default: =`ENABLE_DEBUG`
 - `ENABLE_CURL_MANUAL`:                     Build the man page for curl and enable its `-M`/`--manual` option. Default: `ON`
 - `ENABLE_DEBUG`:                           Enable curl debug features (for developing curl itself). Default: `OFF`
+- `ENABLE_SERVER_DEBUG`:                    Apply curl debug options to test servers. Default: `OFF`
 - `IMPORT_LIB_SUFFIX`:                      Import library suffix. Default: `_imp` for MSVC-like toolchains, otherwise empty.
 - `LIBCURL_OUTPUT_NAME`:                    Basename of the curl library. Default: `libcurl`
 - `PICKY_COMPILER`:                         Enable picky compiler options. Default: `ON`