feat: Support OpenTofu

[lechnerc77]

Purpose

• This PR introduces the support of OpenTofu as called CLI for the import of resources
• It adds the corresponding devcontainer configurations
• It updates the documentation
• Closes [FEATURE] Explore Support of OpenTofu #241

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[X] Feature
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Test the code via automated test

make test

• Additional test steps

Use the CLI with OpenTofu

What to Check

Verify that the following are valid:

• Automated tests are executed successfully

Other Information

A rewrite of the state types might become necessary if the OpenTofu project provides JSON schema for this. As of now we have copied the types in a reduced way from the Terraform types available under MPL

Checklist for reviewer

The following organizational tasks must be completed before merging this PR:

• The PR is assigned to the Project board and a status is set (typically "in review").
• The PR has the matching labels assigned to it.
• The PR has a milestone assigned to it.
• If the PR closes an issue, the issue is referenced.
• Possible follow-up issues are created and linked.

[lechnerc77]

Next Step before merge: After merge of Integration test (#238), execute Integration test on branch

After merge: Rebuild GH Page

[lechnerc77]

Integration test worked: https://github.com/SAP/terraform-exporter-btp/actions/runs/13108246508

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud