Use FALLBACK_ERROR_FORMAT for handlers that return empty()

[Tronic]

Remove mapping of empty() to HTML, such that the fallback format will rather be used. Also removes mapping of file, redirect and other untyped responses.

This has effects on two separate cases:

1. Routes using only the removed types will no longer automatically get any error format
2. Routes using known types (text, json, or html) will now receive corresponding error formats when used with removed types that were conflicting, e.g. json(data) if data else empty() will receive json error format.

When there is no format from route, due to nothing found or a conflict of formats, Sanic falls back FALLBACK_ERROR_FORMAT and other methods. Note that #2668 affects how that is done but does not fix the issue below.

Users affected by this (either now or after merged) are advised to either add accept: application/json or similar header to their request or to define error_format="json" (text, html) on their routes, to get a specific format.

Fix #2658

[codecov]

Codecov Report

Base: 88.583% // Head: 88.642% // Increases project coverage by +0.058% 🎉

Coverage data is based on head (89f2d47) compared to base (9cb9e88).
Patch has no changes to coverable lines.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #2659       +/-   ##
=============================================
+ Coverage   88.583%   88.642%   +0.058%     
=============================================
  Files           87        87               
  Lines         6850      6850               
  Branches      1171      1171               
=============================================
+ Hits          6068      6072        +4     
+ Misses         540       538        -2     
+ Partials       242       240        -2     

Impacted Files	Coverage Δ
sanic/errorpages.py	97.938% <ø> (ø)
sanic/server/websockets/impl.py	38.479% <0.000%> (+0.921%)	⬆️

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[Tronic]

This passed all tests, which means that we definitely need more tests. Will do on another PR, please merge this if OK!

[Tronic]

Linter check is failing on some unchanged files, cannot reproduce locally, all formatted OK here.