chore: updates from crossplane-provider-template

[maximilianbraun]

Description of your changes

I noticed that the provider-template emerged a bit away from the argocd-providers structure, let it be internal instead of pkg for the place for controllers etc, or some updates to the make file which help to create new types. As well as some updates to the Github workflows.

This is an attempt to make it simpler for new contributors to feel home, like with other crossplane providers.

Let me know what you think ✌️

What I did not adjust from provider template:

• Pushing the provider image.
• stale workflow
• updates to integration_test.sh
• dependencies updates (like c-runtime)
• provider.prepare (make) target, which us responsible to rename the template provider to smth meaningful

Necessary follow ups, as soon as #110 is merged:

• we should have a look to also adjust the setup of the controllers (if not already done in #110)
• add the usage tracker (if there is no point why not to do it)
• adjust cmd/provider/main.go with the current c-runtime specific flags

I have:

• [x] Read and followed Crossplane's contribution process.
• [x] Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

• Tests ran successful
• docker image build successfully

[janwillies]

Thank you so much for this! Indeed this provider was created quite a while ago, and new practises have emerged since then. I'm going to take a look at this