feat(agent/agentcontainers): recreate devcontainers concurrently (#18042)

This change introduces a refactor of the devcontainers recreation logic
which is now handled asynchronously rather than being request scoped.
The response was consequently changed from "No Content" to "Accepted" to
reflect this.

A new `Status` field was introduced to the devcontainer struct which
replaces `Running` (bool). This reflects that the devcontainer can now
be in various states (starting, running, stopped or errored).

The status field also protects against multiple concurrent recrations,
as long as they are initiated via the API.

Updates #16424

coderd/apidoc/docs.go

@@ -8613,6 +8613,9 @@ const docTemplate = `{
                         "CoderSessionToken": []
                     }
                 ],
+                "produces": [
+                    "application/json"
+                ],
                 "tags": [
                     "Agents"
                 ],
@@ -8636,8 +8639,11 @@ const docTemplate = `{
                     }
                 ],
                 "responses": {
-                    "204": {
-                        "description": "No Content"
+                    "202": {
+                        "description": "Accepted",
+                        "schema": {
+                            "$ref": "#/definitions/codersdk.Response"
+                        }
                     }
                 }
             }