*: adapt to toml

[xhebox]

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

What problem does this PR solve?

Issue Number: ref #161

Problem Summary: TOML is more convenient in TiDB environment.

What is changed and how it works:

1. all yaml to toml
2. TLS .Warn() logs are changed to .Info()
3. tiproxycli defaults to warn loglevel now, so that the output of commands(e.g. tiproxyctl namespace list) is a operatational TOML output.
4. add make tidy

Check List

Tests

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

tiproxyctl namespace list
tiproxyctl namespace import conf/namespace

• No code

Notable changes

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

Release note

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

None