feat: add env:add command

[Julien-R44]

Okay, so this is something that's been bugging me for a long time. I'm often in the middle of development, and I realize that I need to add an environment variable. And then I have to open 3 different files in my editor: env.example, the .env, and the start/env.ts to add my new variable.

Then I find myself with lots of new tabs open in my IDE, which is a mess. And even without that, it's boring to do manually.

That's why I suggest the env:add command, which works like this:

node ace env:add MY_VARIABLE value --type=string

executing this command will add the variable to the .env.example, .env and start/env.ts files. The variable name will be converted to SCREAMING_SNAKE_CASE.

node ace env:add

executing the command without any arguments/flags will display prompts for each of the required values.

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Small doubt about the env.example: the current implementation adds the value of the variable in the .env.example which can be problematic if people aren't careful before committing: they'll push the values to the repo.

So, if we want to change this, we'd have to add the possibility of having a specific value for the .env.example when using the add method of @adonisjs/env EnvEditor: https://github.com/adonisjs/env/blob/develop/src/editor.ts#L61

I think it makes sense. I'll do a PR if you guys confirm this

[afgallo]

This is great to see! On a related note, I've noticed when I generate a new value for APP_KEY, adonis also adds it to the .env.example file which in my view is problematic. You certainly don't want to accidentally commit this value to a repo. So I think your suggestion is valuable and it makes a lot of sense.

[thetutlage]

Small doubt about the env.example: the current implementation adds the value of the variable in the .env.example which can be problematic if people aren't careful before committing: they'll push the values to the repo.

Yeah, I think we should accept a flag in the EnvEditor that will set an empty value for the key within the .env.example file.

[Julien-R44]

Ready to merge. Documentation updated adonisjs/v6-docs#84