Revise middleware handling

[ahopkins]

This PR aims to:

• introduce an API to control middleware ordering
• performance boost

@app.on_request(priority=99)
async def high_priority(request):
    ...

[codecov]

Codecov Report

Base: 87.844% // Head: 70.943% // Decreases project coverage by -16.900% ⚠️

Coverage data is based on head (09b59d3) compared to base (389363a).
Patch coverage: 87.500% of modified lines in pull request are covered.

❗ Current head 09b59d3 differs from pull request most recent head 38b4ccf. Consider uploading reports for the commit 38b4ccf to get more accurate results

Additional details and impacted files

@@              Coverage Diff               @@
##              main     #2521        +/-   ##
==============================================
- Coverage   87.844%   70.943%   -16.901%     
==============================================
  Files           78        70         -8     
  Lines         6466      5627       -839     
  Branches      1247       972       -275     
==============================================
- Hits          5680      3992      -1688     
- Misses         560      1465       +905     
+ Partials       226       170        -56     

Impacted Files	Coverage Δ
sanic/request.py	48.989% <50.000%> (-45.896%)	⬇️
sanic/middleware.py	92.592% <92.592%> (ø)
sanic/mixins/middleware.py	97.435% <94.736%> (-2.565%)	⬇️
sanic/app.py	83.742% <100.000%> (-3.758%)	⬇️
sanic/signals.py	90.298% <100.000%> (-2.403%)	⬇️
sanic/cookies.py	41.558% <0.000%> (-58.442%)	⬇️
sanic/handlers.py	39.423% <0.000%> (-57.899%)	⬇️
sanic/http/http1.py	35.915% <0.000%> (-49.296%)	⬇️
sanic/response.py	42.487% <0.000%> (-47.136%)	⬇️
... and 44 more

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[ahopkins]

A lot more use cases to consider with some potential breaking changes. Will be safer to kick this one out until after LTS.