This PR extracts dynamic parameter rendering logic from
coderd/parameters.go into a new coderd/dynamicparameters package. Partly
for organization and maintainability, but primarily to be reused in
`wsbuilder` to be leveraged as validation.
Existing template versions do not have the metadata (modules + plan) in
the db. So revert to using static parameter information from the
original template import.
This data will still be served over the websocket.
