chore: rewrite Terraform backend shell script to external Bicep template

[hknutsen]

Rewrite Terraform backend shell script to a Bicep template, and store that template in a separate repository with its own versioning.

Pros:

• A Bicep template should be easier to maintain than a shell script, due to its declarative nature.
• A Bicep template can be deployed without cloning the repo locally.
• Should be able to pass "complex" configuration, such as IP rules and principals IDs, using parameter files that can be checked into Git.

Cons:

• Bicep template does not support taking in a raw Terraform backend configuration file as an input.

[kov117]

Yeah based on what i saw, this looks nice 👍🏼 i liked the new read me file, and its a bit more understandable for my part. Plus if this is easier to maintain compared to shell script then i am all for it.

[sefornes]

As a long-time Windows user from when Microsoft an the *NIX crowd were mortal enemies, I think Bash scripts on Windows is an abomination (much like Powershell on Linux), so I think this is nice.

[hknutsen]

Added a con in the PR description.

[sefornes]

That's pretty trivial, IMO. I think the pros far outweighs it.

[hknutsen]

Experimenting with maintaining this template in a standalone repository: https://github.com/equinor/terraform-backend

Waiting with merge until ewe've decided on something there.

[hknutsen]

Should be ready for re-review 😊