*: ctl TLS refine

[xhebox]

Signed-off-by: xhe xw897002528@gmail.com

What problem does this PR solve?

Issue Number: ref #69

Problem Summary: The main purpose is to enable passing TLSConfig programatically, which makes it embeddable in other applications like operator.

What is changed and how it works:

1. GetRootCmd now accepts tls.Config, the main purpose
2. Silent usage on errors. Only manually print usages on argument mismatch or so.
3. Support passing tls set from cli, and automatically request with or without SSL
4. Fix handling of res.StatusCode != http.StatusOK
5. Handle cases where server with TLS but clients request plain http and vice versa

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

Just enable server with or with TLS and test

One special case is to test !200 cases. Start tiproxy without PD, and you will hit `service not ready` in the first 5 seconds or so 100%.

• No code

Notable changes

• Has configuration change
• Has HTTP API interfaces change (Don't forget to add the declarative for API)
• Has weirctl change
• Other user behavior changes

Release note

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

None