enable build-params evaluation of for-expressions in .bicepparam

[polatengin]

Fixes #14722

Description

build-params now evaluates for-expressions in parameter assignments by expanding them at compile time, avoiding variables() runtime evaluation errors.

I also added coverage for this scenario in both CLI integration tests and core unit tests.

Checklist

• I have read and adhere to the contribution guide.

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 21614500191)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 21614500191

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 21614500191"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 21614500191

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 21614500191"