Add BuildHttpHandler() for serverless apps

[fondoger]

trafficstars

Fix #4892 , #4639

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 94.83%. Comparing base (8690859) to head (c077780). Report is 377 commits behind head on master.

Files with missing lines	Patch %	Lines
rest/server.go	0.00%	6 Missing :warning:

Additional details and impacted files

Files with missing lines	Coverage Δ
rest/server.go	94.00% <0.00%> (-2.54%)	:arrow_down:

... and 20 files with indirect coverage changes

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[kevwan]

Duplicate of #5001