Closes gh-26750

Closes gh-26791

See gh-26678

See gh-26678

Closes gh-22614

Closes gh-26296
See gh-26317

Closes gh-26088

Closes gh-25965

Closes gh-25822

Closes gh-25893
Co-authored-by: Nzhiyi.xx <zhiyi.xx@antfin.com>

Prior to this commit, the resource handler serving static resources for
Spring MVC and Spring WebFlux would always look at the
`Resource#lastModified` information, derive the `"Last-Modified"` HTTP
response header and support HTTP conditional requests with that
information.

In some cases, builds or packaging tools choose to set this last
modification date to a static date in the past. This allows tools to
have reproducible builds or to leverage caching given the static
resources content didn't change.

This can lead to problems where this static date (e.g. "1980-01-01") is
used literally in HTTP responses and will make the HTTP caching
mechanism counter-productive: the content of the resources changed, but
the application insists on saying it didn't change since the 80s...

This commit adds a new configuration option to disable this support -
there is no way to automatically discard those dates: there is no
standard for that and many don't use he "EPOCH 0 date" as it can lead to
compatibility issues with different OSes.

Closes gh-25845

Closes gh-25596

Closes gh-21283

Replace potentially insensitive language with more neutral language.

Closes gh-25314

Closes gh-1035

Closes gh-24945

Closes gh-24875

Closes gh-23915

Closes gh-25006

As of gh-24952, `PathPatternParser` will strictly reject patterns with
`"**"` in the middle of them. `"**"` is only allowed at the end of the
pattern for matching multiple path segments until the end of the path.

Currently, if `"**"` is used in the middle of a pattern it will be
considered as a single `"*"` instead. Rejecting such cases should
clarify the situation.

This commit prepares for that upcoming change and:

* logs a warning message if such a case is used by an application
* expands the MVC and WebFlux documentation about URI matching in
general

Closes gh-24958

Closes gh-24370

Fix "unknown style for example block: INFO"

Issue gh-24427

This commit deprecates PathExtensionContentNegotiationStrategy and
ServletPathExtensionContentNegotiationStrategy and also updates code
that depends on them internally to remove that dependence.

See gh-24179

Closes gh-24304

See gh-24089

Close gh-24030

Closes gh-24008

Closes gh-23958

Closes gh-23954

Closes gh-22396

See gh-23744

This commit introduces reference documentation for WebMvc.fn, the
functional web framework.

Closes gh-23657

See gh-21778