[Breaking Change] Deprecate provider in Bicep configuration files

[shenglol]

Decided to implement this change as a breaking change rather than a soft deprecation because:

1. Handling edge cases where a user specifies both providers and extensions are quite expensive without altering the configuration file binding logic (binding after merging the custom configuration into the built-in configuration).
2. Currently, the providerRegistry experimental feature is used exclusively by the Bicep team internally, so the change poses minimal risk.

Closes #14377.

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 9765195787)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 9765195787

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 9765195787"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 9765195787

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 9765195787"

[github-actions]

Dotnet Test Results

    72 files   -     35      72 suites   - 35   23m 24s ⏱️ - 8m 0s
10 930 tests  -     26  10 929 ✅  -     26  1 💤 ±0  0 ❌ ±0 
25 756 runs   - 12 892  25 754 ✅  - 12 891  2 💤  - 1  0 ❌ ±0 

Results for commit f09851e. ± Comparison against base commit 888a9f9.

♻️ This comment has been updated with latest results.