Support rename cluster

[lucklove]

What problem does this PR solve?

Make it possible to rename cluster.

What is changed and how it works?

Rename the cluster storage folder and reload prometheus and grafana.
eg: tiup cluster rename old new equals to:

mv ~/.tiup/storage/cluster/clusters/old ~/.tiup/storage/cluster/clusters/new
tiup cluster reload new -R grafana,prometheus

Check List

Tests

• Integration test

Side effects

Grafana stores some data related to cluster name to its grafana.db. The rename action will NOT delete them. So there may be some useless panel need to be deleted manually.

Release notes:

Support rename cluster by the command `tiup cluster rename <old-name> <new-name>`
> Grafana stores some data related to cluster name to its grafana.db. The rename action will NOT delete them. So there may be some useless panel need to be deleted manually.

[codecov-commenter]

Codecov Report

Merging #671 into master will increase coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #671      +/-   ##
==========================================
+ Coverage   57.53%   57.59%   +0.06%     
==========================================
  Files         249      250       +1     
  Lines       17891    17920      +29     
==========================================
+ Hits        10293    10321      +28     
- Misses       6248     6249       +1     
  Partials     1350     1350              

Flag	Coverage Δ
#coverage	57.59% <ø> (+0.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...c/github.com/pingcap/tiup/pkg/cluster/api/dmapi.go	61.31% <0.00%> (-1.46%)	⬇️
...src/github.com/pingcap/tiup/pkg/cluster/manager.go	69.05% <0.00%> (-0.48%)	⬇️
.../pingcap/tiup/components/cluster/command/rename.go	71.42% <0.00%> (ø)
...om/pingcap/tiup/components/cluster/command/root.go	45.88% <0.00%> (+0.32%)	⬆️
go/src/github.com/pingcap/tiup/pkg/utils/ioutil.go	49.18% <0.00%> (+1.63%)	⬆️
...c/github.com/pingcap/tiup/pkg/cluster/api/pdapi.go	61.28% <0.00%> (+3.96%)	⬆️

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[lonng]

/merge

[ti-srebot]

/run-all-tests