Refactor: Load new template plugins and be compatible with old formats

[aooohan]

fix #110

[codecov]

Codecov Report

Attention: Patch coverage is 44.76190% with 58 lines in your changes are missing coverage. Please review.

Project coverage is 36.02%. Comparing base (44443bf) to head (4817308).

Files	Patch %	Lines
internal/plugin.go	51.64%	31 Missing and 13 partials ⚠️
internal/manager.go	0.00%	11 Missing ⚠️
internal/luai/vm.go	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #136      +/-   ##
==========================================
- Coverage   36.10%   36.02%   -0.08%     
==========================================
  Files          25       25              
  Lines        2382     2451      +69     
==========================================
+ Hits          860      883      +23     
- Misses       1436     1480      +44     
- Partials       86       88       +2     

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[bytemain]

so in the new plugin system, is nodejs/npmmirror and nodejs/nodejs are maintained in a repo but will release two plugins?

[bytemain]

golang didn't provide a handy assert library, we can use https://pkg.go.dev/github.com/stretchr/testify to simplify the unittest in future

[aooohan]

so in the new plugin system, is nodejs/npmmirror and nodejs/nodejs are maintained in a repo

Yes.

but will release two plugins?

No. It will still be one.

This is just a part of the new plugin system. After finishing this refactor, we will only maintain one plugin vfox-nodjs, which will include all mirrors (We can call them presets), user can use vfox swtich nodejs <preset-name> to switch the mirror they want to use, vfox will use default preset if user doesn't switch.

preset will be a new plugin capability that can be used for many things in the future, for now, it is used as a mirror switch.

Steps for commands after refactoring:

vfox add nodejs # fetch from https://github.com/version-fox/vfox-plugins

vfox swtich nodejs npmmirror # Switch to npmmirror

vfox switch nodejs default # switch to nodejs.org.

vfox swtich nodejs tinsghuamirror 

Feel free to expand, environment variables can also be supported, depending on what the plugin does.

[bytemain]

The test coverage dropped by 0.2 percentage points and it failed to pass. This problem can be solved by configuring a codecov.yml

coverage:
  status:
    project:
      default:
        target: auto
        # allow coverage to drop by this amount and still post success
        threshold: 0.5%
        if_ci_failed: error
    patch: off # no github status notice for coverage of the PR diff.

put a codecov.yml in the root.