Add Provider Sets support to tfctl

[AadarshIBM]

Description

Adds initial Provider Sets support to tfctl using the existing generic resource system.

This is a draft PR and will be updated as I continue working through the remaining Provider Sets CLI implementation.

Completed so far

• Registered provider-sets as a tfctl resource
• Added the provider-set and provset aliases
• Added support for IDs beginning with provset-
• Added the list, view, and create API paths
• Added the default Provider Set output columns
• Hidden configuration-hcl from normal output
• Added registry, completion, and creatable-resource tests
• Kept name-based lookup out of scope for the MVP

Remaining work

• Add list and view command tests
• Add create command tests
• Add safe-output tests
• Add pagination tests
• Validate update and delete workflows
• Finalize project and workspace assignment behavior
• Update documentation and changelog
• Run final end-to-end validation

Testing completed

• go test ./internal/pkg/resource
• go test ./...
• go test ./... -race
• golangci-lint run
• git diff --check

[brandonc]

@AadarshIBM Hello! Thanks for the PR. I have another PR open (#92) and it expands the resource registry to include most resources. I have incorporated your change there.