Add easy install script for Kit CLI

[amisevsk]

Describe the problem you're trying to solve
The KitOps documentation currently supports two install methods:

1. Install via brew
2. Download and unpack a release tarball

When users are in an environment where brew is common (i.e. MacOS) installing Kit is easy; in other environments, it is moderately more difficult, and this is especially the case for installing Kit in Docker containers (which will generally be Linux containers)

Describe the solution you'd like
While running scripts from the internet is generally bad practice, many projects nonetheless provide a simple install script you can download and run to install the project. These scripts make it simpler to install than figuring out the correct release artifact to download. We could store this at a well-known URL and allow users to e.g.

curl get.kitops.org/install.sh | bash

to install Kit.

Describe alternatives you've considered
The alternative for easy installation, especially on linux, would be supporting more package managers, which may be harder to do quickly.

Additional context
Originally mentioned by a user in our Discord

[legorie]

I would like to work on this issue. Below is a first draft which works well on my Ubuntu and Mac. I'll test it on Windows and submit for a review.
https://github.com/legorie/kitops/blob/ft-install/install.sh

[bupd]

Best Approach would be allowing kitops to be used via docker container. (this should work for all platforms)
then we can slowly publish official packages to different linux distros.

Hope this helps

[bupd]

I would like to work on this issue. Below is a first draft which works well on my Ubuntu and Mac. I'll test it on Windows and submit for a review. legorie/kitops@ft-install/install.sh

Hello @legorie I believe you can create a WIP PR with this script.

Here is my review on the above script you have created

1. you cannot support windows only linux and mac will work. I would suggest to remove support for windows here - https://github.com/legorie/kitops/blob/879ae9519710dab3d7fe1e6802e8ae9cdf678691/install.sh#L18
2. also use sh instead of bash since most distros doesn't ship with bash by default. - https://github.com/legorie/kitops/blob/879ae9519710dab3d7fe1e6802e8ae9cdf678691/install.sh#L1

[amisevsk]

Given that install.sh scripts are not good practice at the best of times, if/when we do include an install script I'd largely only be comfortable writing and maintaining it myself (or by trusted committers in the project). The risks are generally too high for this to be a community contribution in my opinion -- sorry I didn't get to this sooner. I'll take a look at the script you've prepared and if it is good enough I'll be sure to credit you with a co-authored-by, though.

@bupd As for running via Docker container, that is already supported -- we maintain both tagged release versions and a rolling next tag (tracking the main branch) in our GitHub packages repo: https://github.com/kitops-ml/kitops/pkgs/container/kitops. The usage guide for the containerized KitOps CLI is available here

[bupd]

@amisevsk I would also believe packages over install scripts. It is much more maintainable that way.

Also simple go install might also work but I am not sure if this is the case here.