transport/grpchttp2: change types to include mem package

[printchard]

Since the mem package is now part of master, we can include the typings into the new framer interface.

RELEASE NOTES: none

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.56%. Comparing base (e524655) to head (32d6bfa).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7477      +/-   ##
==========================================
+ Coverage   81.40%   81.56%   +0.16%     
==========================================
  Files         357      357              
  Lines       27243    27224      -19     
==========================================
+ Hits        22176    22206      +30     
+ Misses       3850     3811      -39     
+ Partials     1217     1207      -10     

Files	Coverage Δ
internal/transport/grpchttp2/framer.go	0.00% <ø> (ø)

... and 23 files with indirect coverage changes

[arvindbr8]

LGTM. Nice work integrating the mem package. One more step closer to the finish line.

cc: @easwars - I'm okay to merge, unless you have any comments

[easwars]

LGTM. Just one minor comment left.