Improve compression logic in CompressionHandler

[sbordet]

Jetty version(s)
12.1.x

Description
CompressionHandler logic should be improved, at least similar to GzipHandler.

• Consider reworking the default configuration. Currently this is done via CompressionConfig.from(MimeTypes), but that method should be moved and be private, because it seems very ad-hoc and not really useful to be public.
• Default CompressionConfig does not have any HTTP methods configured, while GzipHandler had GET and POST.
• Should applications be able to "hint" CompressionHandler about response content encoding?
  For example, if CompressionHandler supports all 3 compression algorithms, can an application explicitly set Content-Encoding: zstd and have CompressionHandler do zstandard compression instead of one of the other?
• Review 304 and etags
• Add minCompressionSize to CompressionConfig.