feat(repository): mounting support

[leonardochaia]

What this PR does / why we need it

This PR adds blob mounting support to the IRepository and its Repository implementation.

Which issue(s) this PR resolves / fixes

Resolves / Fixes #<issue_id>

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]

Codecov Report

Attention: Patch coverage is 91.37931% with 5 lines in your changes missing coverage. Please review.

Project coverage is 81.70%. Comparing base (6d94929) to head (233e79d).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/OrasProject.Oras/Registry/Remote/BlobStore.cs	91.22%	2 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #152      +/-   ##
==========================================
+ Coverage   81.03%   81.70%   +0.66%     
==========================================
  Files          35       35              
  Lines        1060     1104      +44     
  Branches      123      128       +5     
==========================================
+ Hits          859      902      +43     
  Misses        146      146              
- Partials       55       56       +1     

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[shizhMSFT]

Thanks for your contribution! Here's my code review.

[shizhMSFT]

LGTM with suggestions

[Wwwsylvia]

Thanks. This can now be linked to #153.

[Wwwsylvia]

LGTM with nit

[shizhMSFT]

LGTM