*: add json log format support

[csuzhangxc]

What problem does this PR solve?

add json log format support, see internal PRM-327.

What is changed and how it works?

add log-format flag for some binaries.

Check List

Tests

• Manual test (add detailed scripts or steps below)

  • run binary with/without --log-format=json

    [2020/07/17 16:13:11.774 +08:00] [INFO] [printer.go:54] ["Welcome to dm-master"] ["Release Version"=] ["Git Commit Hash"=4f36c144fde76685ebf82d81161bccea326b73b7] ["Git Branch"=json-log] ["UTC Build Time"="2020-07-17 08:11:24"] ["Go Version"="go version go1.13.4 linux/amd64"]
    

    {"level":"INFO","time":"2020/07/17 16:14:08.839 +08:00","caller":"printer.go:54","message":"Welcome to dm-master","Release Version":"","Git Commit Hash":"4f36c144fde76685ebf82d81161bccea326b73b7","Git Branch":"json-log","UTC Build Time":"2020-07-17 08:11:24","Go Version":"go version go1.13.4 linux/amd64"}
    

Code changes

• Has exported function/method change
• Has exported variable/fields change

Related changes

• Need to cherry-pick to the release branch

[lance6716]

do we need to verify user input?

[csuzhangxc]

do we need to verify user input?

@lance6716 do you mean the value of --log-format? the log pkg will verify it, an example

panic: unsupport log format: abc

goroutine 1 [running]:
github.com/pingcap/log.NewTextEncoder(0xc00005e360, 0xc00010c748, 0x4)
        /home/zhangxc/gopath/pkg/mod/github.com/pingcap/log@v0.0.0-20200511115504-543df19646ad/zap_text_encoder.go:168 +0x3fb
github.com/pingcap/log.newZapTextEncoder(...)
        /home/zhangxc/gopath/pkg/mod/github.com/pingcap/log@v0.0.0-20200511115504-543df19646ad/config.go:78
github.com/pingcap/log.InitLoggerWithWriteSyncer(0xc00005e360, 0x22ea920, 0xc0001e8ed0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xc0004d3c18, 0x40cad8)
        /home/zhangxc/gopath/pkg/mod/github.com/pingcap/log@v0.0.0-20200511115504-543df19646ad/log.go:52 +0xc0
github.com/pingcap/log.InitLogger(0xc00005e360, 0x0, 0x0, 0x0, 0x1a5dc1b, 0xc00064a140, 0x0, 0x0)
        /home/zhangxc/gopath/pkg/mod/github.com/pingcap/log@v0.0.0-20200511115504-543df19646ad/log.go:42 +0xb0
github.com/pingcap/dm/pkg/log.InitLogger(0xc0004d3f08, 0x4, 0x1f41f1e)
        /home/zhangxc/gopath/src/github.com/csuzhangxc/dm/pkg/log/log.go:112 +0x141
main.main()
        /home/zhangxc/gopath/src/github.com/csuzhangxc/dm/cmd/dm-master/main.go:47 +0x2b5

[lance6716]

LGTM

[GMHDBJD]

LGTM

[ti-srebot]

cherry pick to release-1.0 failed