Add APP_PROTOCOL env var for app

[ItalyPaleAle]

This PR is the companion of https://github.com/dapr/dapr/pull/6512 which makes the same change in the Dapr Injector.

It adds the APP_PROTOCOL env var for the app that is being started with dapr run. As explained in the PR in dapr/dapr, this is helpful for the app to know if it should start a server with HTTPS or H2C enabled.

[dapr-bot]

This pull request has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in 7 days if no further activity occurs. Please feel free to give a status update now, ping for review, or re-open when it's ready. Thank you for your contributions!

[codecov[bot]]

Codecov Report

Merging #1318 (6c2b992) into master (31b9ea2) will increase coverage by 0.74%. The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master    #1318      +/-   ##
==========================================
+ Coverage   26.81%   27.55%   +0.74%     
==========================================
  Files          39       39              
  Lines        3882     3912      +30     
==========================================
+ Hits         1041     1078      +37     
+ Misses       2767     2757      -10     
- Partials       74       77       +3     

Files Changed	Coverage Δ
pkg/standalone/run.go	12.54% <83.33%> (+12.54%)	:arrow_up:

[dapr-bot]

This pull request has been automatically closed because it has not had activity in the last 37 days. Please feel free to give a status update now, ping for review, or re-open when it's ready. Thank you for your contributions!

[ItalyPaleAle]

Can this be re-opened please? Also, is there something blocking this PR from being merged? @dapr/maintainers-cli @dapr/approvers-cli