cluster: support using provided topo file besides editing it while calling edit-config, add show-config command

[haiboumich]

What problem does this PR solve?

For subcommand tiup cluster edit-config, add a flag --topology-file to allow the user to provide a new topology file to substitute the original one besides editing it.

What is changed and how it works?

• For command edit-config, add a flag --topology-file to allow the user to provide a new topology file to substitute the original one besides editing it.
• add show-config command

Check List

Tests

• Manual test (add detailed scripts or steps below)

1. Build the new tiup-cluster binary and use it as the new component in TiUP central machine.
2. If the flag --topology-file is not specified, it will act like the old flow:
   • Write Topology to a temporary file.
   • Open file in editor.
   • Check and update Topology.
   • Save meta file.
3. Otherwise, it will check the existence of the topology file specified by the flag --topology-file and will only 'Check and update Topology.' and 'Save meta file.'.
4. While executing ./tiup-cluster show-config <cluster-name>, the cluster's config, which is same as the one shown by opening the topology file to edit while executing ./tiup-cluster edit-config <cluster-name>, will be printed in console.

Code changes

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

Related changes

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

Release notes:

* Support using a new topology file to substitute the original one besides editing it while calling `tiup cluster edit-config`
* Add the feature `show-config` of component `tiup-cluster` to show cluster's configuration

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• AstroProfundis

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[codecov-commenter]

Codecov Report

Merging #1637 (25196cd) into master (0ec99bb) will increase coverage by 30.16%.
The diff coverage is 38.59%.

@@             Coverage Diff             @@
##           master    #1637       +/-   ##
===========================================
+ Coverage   15.55%   45.71%   +30.16%     
===========================================
  Files         151      294      +143     
  Lines       15275    26912    +11637     
===========================================
+ Hits         2376    12303     +9927     
- Misses      12382    12711      +329     
- Partials      517     1898     +1381     

Flag	Coverage Δ
cluster	37.03% <35.18%> (?)
dm	26.13% <31.70%> (?)
integrate	45.71% <38.59%> (+30.16%)	⬆️
playground	13.31% <ø> (?)
tiup	15.57% <ø> (+0.01%)	⬆️
unittest	∅ <ø> (∅)

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

Impacted Files	Coverage Δ
pkg/cluster/manager/show_config.go	0.00% <0.00%> (ø)
pkg/cluster/manager/edit_config.go	32.43% <38.46%> (ø)
components/cluster/command/show_config.go	41.66% <41.66%> (ø)
components/cluster/command/edit_config.go	85.71% <100.00%> (ø)
components/cluster/command/root.go	44.35% <100.00%> (ø)
components/dm/command/edit_config.go	83.33% <100.00%> (ø)
components/playground/instance/tiflash_config.go	100.00% <0.00%> (ø)
components/dm/command/destroy.go	63.15% <0.00%> (ø)
components/cluster/command/enable.go	43.75% <0.00%> (ø)
... and 237 more

---

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[AstroProfundis]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 25196cd