Separate ASGI request and lifespan callables

[ahopkins]

I noticed some breaks in ASGI implementation. This should largely have no impact on how Sanic performs with ASGI, but creates a cleaner separation between the ASGIApp (which is now exclusively for request handling) and Lifespan (which now has top level treatment in the Sanic.__call__ method).

[codecov]

Codecov Report

Patch coverage: 91.379% and project coverage change: +0.019 🎉

Comparison is base (08a81c8) 88.587% compared to head (b077fd1) 88.607%.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #2646       +/-   ##
=============================================
+ Coverage   88.587%   88.607%   +0.019%     
=============================================
  Files           87        87               
  Lines         6817      6820        +3     
  Branches      1172      1171        -1     
=============================================
+ Hits          6039      6043        +4     
  Misses         535       535               
+ Partials       243       242        -1     

Impacted Files	Coverage Δ
sanic/app.py	89.752% <75.000%> (-0.301%)	⬇️
sanic/asgi.py	91.538% <94.000%> (-0.770%)	⬇️

... and 1 file with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[Kludex]

👍