feat: accept include_related query param on get workspace by ID - #29233

Part of the lite codersdk.Workspace work (GRU-82, RFC). Follows #28639, which added the wsrelated package and parser.

Wires the include_related query parameter into GET /api/v2/workspaces/{workspace}, the first endpoint to accept it. When present, the value is parsed with wsrelated.Parse and the resulting selection is threaded into workspaceData, so only the requested related data is queried. Omitting the parameter is backward compatible and returns everything (wsrelated.All). An invalid value returns 400.

Because related data can now be omitted, the handler no longer assumes the build and template are present: it uses zero values when they are absent, and only enforces the template read-authorization check (403) when the template was actually requested.

Partial-build conversion

convertWorkspaceBuilds now tolerates a build whose provisioner job or template version was deliberately omitted from the selection, so selections such as latest_build (build only) or latest_build.resources.* (resources without the job) convert correctly instead of erroring. The omitted fields are left zero (empty Job, empty TemplateVersionName). Resources are keyed by the build's JobID rather than the fetched job row, so they load independently of whether the job is selected. The integrity error is preserved for full-data callers: when a job or template version is requested but missing, conversion still fails. The selection config (wsrelated.LatestBuild) is threaded into convertWorkspaceBuilds to distinguish "not requested" from "missing".

Only this endpoint is wired; the other endpoints that produce codersdk.Workspace objects, and the codersdk client functions, come in later PRs.

Generated by Coder Agents on behalf of @spikecurtis.