api, pdctl: add HTTP Component signature

[CabinfeverB]

What problem does this PR solve?

close #4490 and related to #3111

This PR is going to support HTTP component signature

What is changed and how it works?

It adds a RoundTripper for adding a component signature header to every request and applies it to pdctl. (other components outside PD could add header by themselves)

For the test, this PR creates a test server and registers a temp handler for /pd/api/v1/health(just for test) and sends the request by health pdctl cmd.

Check List

Tests

• Unit test

Release note

add HTTP Component signature

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• bufferflies
• disksing

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[codecov]

Codecov Report

Merging #4491 (4c81e19) into master (909f2fd) will decrease coverage by 0.12%.
The diff coverage is 73.33%.

@@            Coverage Diff             @@
##           master    #4491      +/-   ##
==========================================
- Coverage   74.95%   74.83%   -0.13%     
==========================================
  Files         264      264              
  Lines       27921    27933      +12     
==========================================
- Hits        20929    20904      -25     
- Misses       5127     5158      +31     
- Partials     1865     1871       +6     

Flag	Coverage Δ
unittests	74.83% <73.33%> (-0.13%)	⬇️

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

Impacted Files	Coverage Δ
tools/pd-ctl/pdctl/command/global.go	70.17% <0.00%> (+0.61%)	⬆️
pkg/apiutil/apiutil.go	65.38% <80.00%> (+3.47%)	⬆️
tests/pdctl/helper.go	100.00% <100.00%> (ø)
pkg/errs/errs.go	75.00% <0.00%> (-25.00%)	⬇️
server/kv/etcd_kv.go	69.56% <0.00%> (-10.15%)	⬇️
server/tso/local_allocator.go	64.86% <0.00%> (-6.76%)	⬇️
server/region_syncer/client.go	79.68% <0.00%> (-3.91%)	⬇️
server/tso/tso.go	60.22% <0.00%> (-1.71%)	⬇️
server/tso/allocator_manager.go	63.22% <0.00%> (-1.50%)	⬇️
server/server.go	71.49% <0.00%> (-1.35%)	⬇️
... and 8 more

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[nolouch]

lgtm. but ci failed.

[CabinfeverB]

/run-unit-test

[nolouch]

/merge

[ti-chi-bot]

@nolouch: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 34d403f

[ti-chi-bot]

@CabinfeverB: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.