config, info: add config proxy.advertise-addr

[djshow832]

What problem does this PR solve?

Issue Number: close #494

Problem Summary:
TiProxy registers its IP to ETCD and TiDB/TiDB-Dashboard queries its config/pprof through IP, while the certificates in TiProxy may only contain DNS (especially in k8s) and the query fails.

What is changed and how it works:
Add proxy.advertise-addr to the config. Later, I'll update TiUP and TiDB-Operator to pass the DNS in the config.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Notable changes

• Has configuration change
• Has HTTP API interfaces change
• Has tiproxyctl change
• Other user behavior changes

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

- Add configuration `proxy.advertise-addr`

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

❗ No coverage uploaded for pull request base (main@d58674c). Click here to learn what that means.

Additional details and impacted files

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##             main     #495   +/-   ##
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  Coverage        ?   64.41%           
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  Files           ?       61           
  Lines           ?     5814           
  Branches        ?        0           
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  Hits            ?     3745           
  Misses          ?     1781           
  Partials        ?      288           

Flag	Coverage Δ
unit	64.41% <100.00%> (?)

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: xhebox

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-03-27 08:29:23.523146823 +0000 UTC m=+2056590.545393234: ☑️ agreed by xhebox.