test: noop blobstore

[volmedo]

Resolves #33

This PR adds a new command line flag --use-noop-blobstore that can be used to start the storage node with the blobstore disabled. This is useful in testing scenarios to speed tests up and avoid storage and data transfer charges.

Alternatively, setting the env variable STORAGE_USE_NOOP_BLOBSTORE=1 will have the same effect.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/start.go	0.00%	6 Missing ⚠️
pkg/store/blobstore/noop.go	0.00%	6 Missing ⚠️

Files with missing lines	Coverage Δ
cmd/start.go	0.00% <0.00%> (ø)
pkg/store/blobstore/noop.go	0.00% <0.00%> (ø)

... and 16 files with indirect coverage changes