feat: add cache isolation

[binbin-li]

Description

What this PR does / why we need it:

1. Add a context util to pass namespace through context so that namespace can be consumed by all components in a request.
2. Refactor cache to prefix the namespace to the cache key so that cache can be isolated by namespace.
3. This PR is just adding cache isolation support which could be utilized once we actually take namespace in.

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

Part of issue: #743

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Helm Chart Change (any edit/addition/update that is necessary for changes merged to the main branch)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also list any relevant details for your test configuration

• Test A
• Test B

Checklist:

• Does the affected code have corresponding tests?
• Are the changes documented, not just with inline documentation, but also with conceptual documentation such as an overview of a new feature, or task-based documentation like a tutorial? Consider if this change should be announced on your project blog.
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have appropriate license header?

Post Merge Requirements

• MAINTAINERS: manually trigger the "Publish Package" workflow after merging any PR that indicates Helm Chart Change

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (5f33fd8) 55.31% compared to head (6b4a987) 55.40%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1213      +/-   ##
==========================================
+ Coverage   55.31%   55.40%   +0.09%     
==========================================
  Files         104      105       +1     
  Lines        6902     6916      +14     
==========================================
+ Hits         3818     3832      +14     
  Misses       2749     2749              
  Partials      335      335              

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[susanshi]

LGTM.

[junczhu]

LGTM