add client method to generate TLE struct

[bobcallaway]

Summary

Adds helper method in github.com/sigstore/rekor/pkg/client to generate https://pkg.go.dev/github.com/sigstore/protobuf-specs@v0.1.0/gen/pb-go/rekor/v1#TransparencyLogEntry from an entry retrieved from a Rekor instance

Release Note

• New method in github.com/sigstore/rekor/pkg/client to generate https://pkg.go.dev/github.com/sigstore/protobuf-specs@v0.1.0/gen/pb-go/rekor/v1#TransparencyLogEntry from an entry retrieved from a Rekor instance

[codecov]

Codecov Report

Merging #1498 (9be4166) into main (f1bdca8) will increase coverage by 20.27%.
The diff coverage is 77.94%.

@@             Coverage Diff             @@
##             main    #1498       +/-   ##
===========================================
+ Coverage   46.85%   67.13%   +20.27%     
===========================================
  Files          72       82       +10     
  Lines        7401     8392      +991     
===========================================
+ Hits         3468     5634     +2166     
+ Misses       3592     2089     -1503     
- Partials      341      669      +328     

Flag	Coverage Δ
e2etests	48.51% <1.47%> (?)
unittests	47.86% <91.37%> (+1.00%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cmd/rekor-cli/app/format/wrap.go	40.62% <0.00%> (ø)
cmd/rekor-cli/app/get.go	49.66% <0.00%> (+47.60%)	⬆️
pkg/client/rekor_client.go	94.31% <96.29%> (+3.14%)	⬆️
cmd/rekor-cli/app/pflags.go	90.30% <100.00%> (ø)

... and 55 files with indirect coverage changes

[bobcallaway]

I'll make the CLI changes in a different PR

[wlynch]

Thanks for doing this!