feat: reinitialize agents when a prebuilt workspace is claimed (#17475)

This pull request allows coder workspace agents to be reinitialized when
a prebuilt workspace is claimed by a user. This facilitates the transfer
of ownership between the anonymous prebuilds system user and the new
owner of the workspace.

Only a single agent per prebuilt workspace is supported for now, but
plumbing has already been done to facilitate the seamless transition to
multi-agent support.

---------

Signed-off-by: Danny Kopping <dannykopping@gmail.com>
Co-authored-by: Danny Kopping <dannykopping@gmail.com>

coderd/apidoc/swagger.json

@@ -7463,6 +7463,27 @@
 				}
 			}
 		},
+		"/workspaceagents/me/reinit": {
+			"get": {
+				"security": [
+					{
+						"CoderSessionToken": []
+					}
+				],
+				"produces": ["application/json"],
+				"tags": ["Agents"],
+				"summary": "Get workspace agent reinitialization",
+				"operationId": "get-workspace-agent-reinitialization",
+				"responses": {
+					"200": {
+						"description": "OK",
+						"schema": {
+							"$ref": "#/definitions/agentsdk.ReinitializationEvent"
+						}
+					}
+				}
+			}
+		},
 		"/workspaceagents/me/rpc": {
 			"get": {
 				"security": [
@@ -9302,6 +9323,22 @@
 				}
 			}
 		},
+		"agentsdk.ReinitializationEvent": {
+			"type": "object",
+			"properties": {
+				"reason": {
+					"$ref": "#/definitions/agentsdk.ReinitializationReason"
+				},
+				"workspaceID": {
+					"type": "string"
+				}
+			}
+		},
+		"agentsdk.ReinitializationReason": {
+			"type": "string",
+			"enum": ["prebuild_claimed"],
+			"x-enum-varnames": ["ReinitializeReasonPrebuildClaimed"]
+		},
 		"aisdk.Attachment": {
 			"type": "object",
 			"properties": {