feature: Adds utility functions to add envars and update Redwood toml for plugin packages to cli helpers for use in simplifying CLI setup commands

[dthyresson]

When writing a CLI plugin for setup and custom commands, there are a number of tasks that almost always done:

• adding an envar
• updating redwood.toml to setup the new plugin

This PR:

• adds a utility function to add the envar and uses in the the addEnvVarTask
• this function now ensures no duplicate envars are added if setup/command is run more than once
• updates the tmp to setup the

[experimental.cli]
  autoInstall = true
  [[experimental.cli.plugins]]
    package = "@unkey/redwoodjs"

section for a given package.

Tests are included.

[Josh-Walker-GM]

I haven't run this yet so sorry for the early comments. I don't want to appear like I'm nit picking because I certainly don't mean to. I also might be wrong on my comments since I haven't run it to confirm so feel free to discard anything that is wrong.

I'll try this out a little later today.

[Josh-Walker-GM]

I think there could be a potential issue here around the defaults redwood adds.

This getConfig function does a few things:

• Reads the toml
• Performs env var interpolation
• Adds defaults

You can see the line here:

redwood/packages/project-config/src/config.ts

Line 203 in 8e59d91

return merge(DEFAULT_CONFIG, getRawConfig(configPath))

Then the CLI plugin defaults are here:

redwood/packages/project-config/src/config.ts

Lines 176 to 186 in 8e59d91

	cli: {
	autoInstall: true,
	plugins: [
	{
	package: '@redwoodjs/cli-storybook',
	},
	{
	package: '@redwoodjs/cli-data-migrate',
	},
	],
	},

This would mean even though these CLI options are not in the user toml they are in the value returned from getConfig. This is the difference between getConfig and getRawConfig.

Looking again I'm not sure this would result in invalid toml output but it might have made your logic a little more complicated here? I'm not sure so just adding this for visibility into my thinking right now

[Josh-Walker-GM]

Looks good and will be useful to plugin authors for sure! I haven't run/used these myself but reading over the code it looks good and the test coverage is good. Happy to approve for sure!