XD-954: Provide DSL completion for simple cases

Wire completion provider to the REST layer and Shell

Fix trailing space handling

Add parser recovery logic

Generalize provider logic = recoveries | expansions

Change tests to accommodate new parser behavior

Fix counter module options following rebase

Fix fallthrough warning

Fix serial version warning

Fix generics warnings

Fix typos

Rename strategy methods

Rename CodeCompletion -> Completion

Reference issue numbers in ignored tests

Rename CompletionKind.composed to module

Rename CodeCompletion -> Completion

Use Spring SHL SNAPSHOT