*: another operator adapt PR

[xhebox]

What problem does this PR solve?

Issue Number: ref #69

Problem Summary:

What is changed and how it works:

1. remove auto-certs for server-tls/cluster-tls, disable proxy SQL tls by default to speed up the startup speedb by default(generate certs on fly is slow).
2. remove skip-ca for cluster-tls, disable TLS to connect PD by default. PD does not enable TLS by default.
3. add ./bin/weirctl config get(get /api/admin/config/proxy/) command
4. if etcd-kv/config/proxy not present, set it. It is like the default namespace.
5. For configManager.watch(). Watch Rev() will not query the old data as Rev()-1, but will stilly query the current data compared to rev == 0 or rev == -1(equaivlent to WithCreated()
6. removed all weir stuff in the source code
7. if you mv ./bin/tiproxy ./bin/xxproxy, the help message will print xxproxy instead of tiproxy
8. downgrade /lib mod to go1.16. Because operator is using CI of go 1.13, I must use a lower version. And operator has Upgrade go to 1.16 tidb-operator#4706 , so it will be downgraded to 1.16 before operator supports 1.19. Peformance is not affected since when compiling the proxy because MVS algo will pick go 1.19 for the whole project including /lib module.

Check List

Tests

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

./weirproxy
echo '{"max-connections":1}' | ./bin/weirctl config proxy set
./bin/weirctl config proxy get
check max connections by mycli -u root -P 6000

• 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

[djshow832]

TestProxyConfig failed.

[xhebox]

TestProxyConfig failed.

Stablized. Force clear the channel to skip the first created event.