improve install process

[code-IM-perfect]

Kvantum manager does not allow batch install and all it does in the backend is copy the folder to ~/.config/kvantum, so I changed the install process to install all the themes at once. (it can be a pain in the ass to install them individually)

The desired flavor can then be chosen from Kvantum Manager itself as if it was installed from it.

Also added the logical in-betweens like cloning etc

[code-IM-perfect]

@sgoudham pls review

[code-IM-perfect]

Is there an issue with this approach?

[sgoudham]

Is there an issue with this approach?

Sorry, this is fairly low priority for me so I haven't gotten around to it until now.

When it comes to ports that simply require you to move file(s) from the repository to a location in your file system. I've actually started to favour and recommend simply saying "Download the file from x...." instead of providing the whole git clone and something like curl or wget commands.

Ultimately, it comes down to the fact that we don't want people to blindly copy/paste commands from the README without understanding what they do. Also this can open up to PRs where some people have issues with curl because of their system and then open a PR to use wget and then wget breaks for another set of users...

Granted, in this case, it's fairly mild since it's git clone and cp but I'd rather leave it as general as possible and the user can decide how to copy files to their system. I'd be very surprised if someone wants to rice/theme their Linux operating system and did not know of the cp command already.

I hope you can understand my reasoning on why I'm not so keen on accepting this PR atm. I'm open to have a discussion if you really do feel these commands need to exist on the README.