SubmitChangeRequestModal Component breaking change request functionality

[adamc-sp]

As initially reported in terminusdb/terminusdb#2116, when you attempt to use the change request functionality, you end up with a blank screen and nothing actually changing.

This looks like multiple components being broken due to Alert not being defined, an example of this is when submitting a change request for approval, as per this line in this file:

https://github.com/terminusdb/terminusdb-dashboard/blob/main/packages/tdb-dashboard/src/components/SubmitChangeRequestModal.js#L45