Composer 2 support

[alxy]

Initial attempt to fix #50

• Use composer create-project october/october to install october. This is the new preferred way to install October from version 1.1.0 on. It also requires less hacks, e.g. to load the .htaccess file and works with Composer 2.
• Bump the installed October version to 1.1.* (Maybe this can be automated or configurable?)
• Install additional composer dependecies after plugins have been installed. Reason: If a plugin is installed via git remote and does have composer dependencies, those are only installed if we run composer install after the installation.
• Bump to a new major version 1.0.0. Probably it is a good idea to have a separate branch for this version?

[tobias-kuendig]

I'll wait with this PR for two reasons:

• There is still an ongoing issue regarding composer 2 compatibility: https://github.com/octobercms/october/issues/5033
• We'll wait on the October 1.1 update until it is officially released

[alxy]

Fair points, just wanted to point out that the current develop branch of october does indeed work with Composer 2 as a custom fork of the merge-plugin is used that is compatible with version 2: https://github.com/octobercms/october/blob/develop/composer.json#L46

[yersey]

@alxy What about .htaccess. What if it doesn't exist.