Support use local file or directory as config for monitor components

[lucklove]

TODOLIST:

• Support config alertmanager
• Support config prometheus
• Support config grafana
• Add unit test
• Add integration test

What problem does this PR solve?

• Support config alertmanager
• Support config prometheus rules
• Support config grafana dashboards

What is changed and how it works?

Make it possible to specify additional file (or dir) path in topology or meta.yml. In deploy and reload stage, tiup will copy these things to remote.

Check List

Tests

• Unit test
• Integration test

Code changes

• Has exported variable/fields change
• Has persistent data change

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

Support config monitor components

[codecov-commenter]

Codecov Report

Merging #712 into master will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #712      +/-   ##
==========================================
+ Coverage   57.97%   58.00%   +0.02%     
==========================================
  Files         253      253              
  Lines       18530    18660     +130     
==========================================
+ Hits        10743    10823      +80     
- Misses       6365     6397      +32     
- Partials     1422     1440      +18     

Flag	Coverage Δ
#coverage	58.00% <ø> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
...p/tiup/pkg/cluster/template/config/alertmanager.go	64.70% <0.00%> (-8.63%)	⬇️
...ub.com/pingcap/tiup/pkg/cluster/spec/prometheus.go	73.87% <0.00%> (-4.70%)	⬇️
....com/pingcap/tiup/components/dm/spec/prometheus.go	69.42% <0.00%> (-3.31%)	⬇️
...thub.com/pingcap/tiup/pkg/cluster/spec/instance.go	71.79% <0.00%> (-3.21%)	⬇️
...hub.com/pingcap/tiup/components/dm/spec/grafana.go	63.01% <0.00%> (-1.79%)	⬇️
...hub.com/pingcap/tiup/pkg/cluster/executor/local.go	69.56% <0.00%> (-1.27%)	⬇️
...om/pingcap/tiup/components/dm/spec/alertmanager.go	68.91% <0.00%> (-0.65%)	⬇️
...com/pingcap/tiup/components/dm/spec/topology_dm.go	73.36% <0.00%> (-0.41%)	⬇️
....com/pingcap/tiup/pkg/cluster/spec/alertmanager.go	64.40% <0.00%> (ø)
...thub.com/pingcap/tiup/pkg/cluster/spec/validate.go	96.78% <0.00%> (+0.16%)	⬆️
... and 2 more

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[lonng]

Can those *.json can be generated dynamically?

[lucklove]

Can those *.json can be generated dynamically?

No, they have too many things.
However, in tests, we can generate the simplest ones, but it's of no significance since we can just replace these with local file (which are simplified)

[AstroProfundis]

LGTM