perf: reduce auth request count for oras cp

[qweeah]

What this PR does / why we need it:
This PR reduces the auth request sent to destination registry of oras cp

Before

request: HEAD manifest digest - 401
request: POST token (scope: pull) - 200
request: HEAD manifest digest  - 404
...
request: HEAD blob digest - 404
request: POST blob - 401
request: POST token (scope: pull, push) - 200
request: POST blob - 202
request: PUT blob - 201

After

request: HEAD manifest digest - 401
request: POST token (scope: pull, push) - 200
request: HEAD manifest digest  - 404
...
request: HEAD blob digest - 404
request: POST blob - 202
request: PUT blob - 201

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1105

Please check the following list:

• Does the affected code have corresponding tests, e.g. unit test, E2E test?
• Does this change require a documentation update?
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have an appropriate license header?

[codecov-commenter]

Codecov Report

Merging #1142 (ac81631) into main (0744892) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

@@            Coverage Diff             @@
##             main    #1142      +/-   ##
==========================================
+ Coverage   80.12%   80.14%   +0.01%     
==========================================
  Files          57       57              
  Lines        2994     2996       +2     
==========================================
+ Hits         2399     2401       +2     
  Misses        410      410              
  Partials      185      185              

Files	Coverage Δ
cmd/oras/root/cp.go	81.70% <100.00%> (+0.34%)	⬆️
internal/registryutil/auth.go	100.00% <100.00%> (ø)

[Wwwsylvia]

Wrong reference, please ignore.

[Wwwsylvia]

Should the PR title start with just perf:?🤔

[Wwwsylvia]

LGTM, but I am not a maintainer.

[TerryHowe]

/lgtm

[shizhMSFT]

LGTM