Add gitignore to allow app within repo

[zoglo]

QoL Developer improvements

TL;DR

This PR improves QoL for developers working on the contao-demo

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Description

This PR allows installing Contao within the cloned repository by git-ignoring the usual folders and adding the allowed plugins within composer.json. This allows developers to work within the cloned repository and install the demo within it.

I made sure that the var/backups folder is not excluded, so it allows uploading the backups (contao:backup:restore)

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Edit

• this change can be upstreamed into the 5.2.* branch (main)

[aschempp]

I'm not 100% sure this makes sense. Why would you clone that repository? And when using composer create-project contao/contao-demo, wouldn't the .gitignore make sense then as well?

I think it can be suboptimal to include developer stuff in a demo project that is clearly designed to be a "starting point" for people not familiar with the project. Regardless of that, shouldn't the .gitignore file be exactly the same as https://github.com/contao/managed-edition/blob/5.x/.gitignore if we actually add one?

[zoglo]

Why would you clone that repository?

If you are working on updates to the demo, such as bug fixes, but it may be a one-time thing for most.

I'm not 100% sure this makes sense. Why would you clone that repository? And when using composer create-project contao/contao-demo, wouldn't the .gitignore make sense then as well?

I think it can be suboptimal to include developer stuff in a demo project that is clearly designed to be a "starting point" for people not familiar with the project. Regardless of that, shouldn't the .gitignore file be exactly the same as https://github.com/contao/managed-edition/blob/5.x/.gitignore if we actually add one?

You are right on not using the developer files within a demo to help people, but most people install it via composer create-project, hence the .giattributes that ignores the .gitignore, so it'll never be within vendor nor in your root anyway.

What I removed in my latest commit is:

• the parameters.yml as it's outdated
• the .env (added it to my .git/info/exclude)
• the .git (added it to my .git/info/exclude)

I agree with using the same gitignore as in the Contao project, but it does include lines like:

• /files/ - We would actually want them in the demo theme due to the css files
• /templates - We want these included in the theme as well
• !/var/backups/ - We don't want var, but we need the backups folder for the backup:restore command

What we would never want to push would be the following files, that are usually part of my .git/info/exclude but not everyone sets them up:

• !/system/config - Not needed in this demo, I exluded the whole /system/ folder (The system settings don't need to be part and were never pushed)
• /composer.lock - Do we want a composer install to install an outdated version?

However, if we let the .gitattributes within this PR, the .gitignore will never appear within vendor nor in the root directory.

Wdyt @aschempp ?

(My initial idea was to add a global gitignore file that would work for most platforms and IDE)

[aschempp]

Maybe we should rather add this to the Contributing section in the readme? Here's what my local .gitignore looks like for developing the demo:

/assets
/bin
/public
/system
/var/*
!/var/backups
/vendor
/composer.lock
/.gitignore
/.env*

[zoglo]

Closing this as I'm using the local variant as well nowadays.