add kubelet certificate mode in yurthub

[rambohe-ch]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:
/kind bug
/kind documentation
/kind enhancement
/kind good-first-issue
/kind feature
/kind question
/kind design
/sig ai
/sig iot
/sig network
/sig storage

/kind feature

What this PR does / why we need it:

add a new bootstrap mode: kubeletcertificate for yurthub component, so yurthub can use kubelet certificate to work.

Which issue(s) this PR fixes:

Fixes #1618

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

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In response to this:

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:
/kind bug
/kind documentation
/kind enhancement
/kind good-first-issue
/kind feature
/kind question
/kind design
/sig ai
/sig iot
/sig network
/sig storage

/kind feature

What this PR does / why we need it:

add a new bootstrap mode: kubeletcertificate for yurthub component, so yurthub can use kubelet certificate to work.

Which issue(s) this PR fixes:

Fixes #1618

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

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[openyurt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rambohe-ch

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• OWNERS [rambohe-ch]

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
4 Code Smells

No Coverage information
1.4% Duplication

[codecov]

Codecov Report

Merging #1625 (bfa5aa6) into master (fe46a9d) will decrease coverage by 0.58%.
The diff coverage is 59.47%.

@@            Coverage Diff             @@
##           master    #1625      +/-   ##
==========================================
- Coverage   51.43%   50.85%   -0.58%     
==========================================
  Files         134      137       +3     
  Lines       15947    16029      +82     
==========================================
- Hits         8202     8152      -50     
- Misses       7000     7137     +137     
+ Partials      745      740       -5     

Flag	Coverage Δ
unittests	50.85% <59.47%> (-0.58%)	⬇️

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

Impacted Files	Coverage Δ
pkg/yurthub/certificate/server/server.go	39.02% <39.02%> (ø)
...tificate/kubeletcertificate/kubelet_certificate.go	43.63% <43.63%> (ø)
cmd/yurthub/app/config/config.go	48.97% <72.72%> (-3.44%)	⬇️
pkg/yurthub/certificate/token/token.go	26.84% <75.00%> (-30.16%)	⬇️
pkg/yurthub/certificate/manager/manager.go	78.46% <78.46%> (ø)
cmd/yurthub/app/options/options.go	94.79% <100.00%> (+0.06%)	⬆️

... and 1 file with indirect coverage changes

[YTGhost]

/lgtm