Issue #12397 - Add more default excludes to GzipHandler.

[joakime]

• Exclude more compressed mime-types
• Exclude more compressed path extensions
• Add missing compressed file types to mime.properties

Fixes: #12397

[joakime]

@gregw with this change, I see yet another thing that MimeTypes should probably do (flag if a mime-type represents compressed content that shouldn't be recompressed).

What do you think about refactoring the MimeTypes configuration files a great deal?

We could use json, and our jetty-util-ajax lib ...

[
  "application/gzip" : {
    "extensions": [ ".gz", ".gzip" ],
    "assumedCharset": "",
    "inferredCharset": ""
    "ignoreCharset": "true"
    "compressedType": "true"
  },
  "application/json" : {
    "extensions": [ ".json" ],
    "assumedCharset": "utf-8",
    "inferredCharset": ""
    "ignoreCharset": "false"
    "compressedType": "false"
  }
]

The idea is that this becomes our preferred configuration file, but we still allow the use of the older mime.properties and encoding.properties as an alternate deprecated configuration technique.