Add custom output formats

[bep]

See https://discuss.gohugo.io/t/custom-output-content-types/4584

Issues that this issue will also solve (will check):

• [x] Upper case tags #1641
• [x] Pagination links #2110 #2374 #1252
• [x] Ugly URL ambiguity #3102
• [x] Taxonomies vs ugly #1989
• [x] Dots #1885
• [x] Permalink for lang roots + ugly #3179
• [x] #320 configurable file ext
• [x] #2995 template lookup theme vs project

Other TODOS:

• [x] Rewrite pageLayoutIdentifier to use the descriptor/adapter pattern.
• [x] HandleTODO(bep) output
• [x] Rename OutputType => OutputFormat
• [x] Remove siteWriter.
• [x] Read Output formats from site config
• [x] Read Output format definitions from site config => #3222
• [x] Read Media types from site config => #3223
• [x] * Handle types in aliases
• [x] Add Page.OutPutFormats with Permalink, RelPermalink + a way to find AMP etc.
• [x] Base template handling
• [x] Partial handling
• [x] Text vs HTML templates => #3221
• [x] * Stats report
• [x] Ref vs relref => #3224
• [x] Register MIME types in server
• [x] * Handle protocol
• [x] * There is a panic in the themes site build with this branch.
• [x] Check injector + replacements vs suffix

[github-actions[bot]]

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