Feat: Create `add` cmd script to use Rspack

[sunker]

Which areas does this feature request relate to

• Create Plugin
• Sign Plugin
• Plugin E2E
• Plugin Meta Extractor
• Documentation

Problem

To use Rspack instead of Webpack, one can set the useExperimentalRspack flag to true when scaffolding new plugins. However, since migrations-as-updates was introduced recently, feature flags are no longer being honoured when running the update cmd.

Solution

Create an addition script that allows plugin devs to optionally enable this capability. We can then remove the logic related to the useExperimentalRspack feature toggle inside our templates.

Alternatives

No response

Additional context

No response

Are you interested in contributing the solution?

• Yes
• No