refactor: rename plugins config file to igniteapps

[jeronimoalbi]

No description provided.

[jeronimoalbi]

This PR would require a migration step in the docs that requires the user to:

1. Rename the plugins: section in plugins.yml to apps: in the global and local blockchain app config files
2. Rename $HOME/.ignite/plugins/plugins.yml to $HOME/.ignite/plugins/igniteapps.yml (global config)
3. Rename $HOME/.ignite/plugins to $HOME/.ignite/apps
4. Rename plugins.yml to igniteapps.yml in any blockchain app (local config)

If we decide to document it I can add it as part of this PR.

Alternatively we can use ignite doctor to automate the process, so the only required step to migrate to the new CLI version is to run the doctor command.

[github-actions]

Visit the preview URL for this PR (updated for commit b2196f3):

https://igntservices-docs--pr3669-refactor-plugins-con-bz85tb15.web.app

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[jeronimoalbi]

I'm adding the plugin config migration to the doctor command within this PR

[julienrbrt]

I don't understand why not everything is being renamed. Am I missing something?

Edit: I realize that this PR is only about the file renaming now 🤔

[julienrbrt]

utACK