Daml-Script changes for 2.9

[samuel-williams-da]

Backport of #19223

Doesn't include the package preference tests, as we don't have the testing structure backported yet
Also adds daml-script-beta as an alias to daml3-script in the daml.yaml, with a slightly different warning

[samuel-williams-da]

Also, haven't yet found a nicer name for concurrently, open to suggestions

[paulbrauner-da]

Thanks for making all these necessary changes quickly! Have you tested that daml-script-beta works as intended?

[paulbrauner-da]

Also, haven't yet found a nicer name for concurrently, open to suggestions

concurrently is canon in haskell land https://hackage.haskell.org/package/async-2.2.5/docs/Control-Concurrent-Async.html#v:concurrently :)

[samuel-williams-da]

Thanks for making all these necessary changes quickly! Have you tested that daml-script-beta works as intended?

Yes :)

concurrently is canon in haskell land

Right, but in haskell land it does a lot more than this one!