Allow .zed/tasks.json local configs (#8536)

![image](https://github.com/zed-industries/zed/assets/2690773/e1511777-b4ca-469e-8636-1e513b615368)

Follow-up of
https://github.com/zed-industries/zed/issues/7108#issuecomment-1960746397

Makes more clear where each task came from, auto (re)load
.zed/config.json changes, properly filtering out other worktree tasks.

Release Notes:

- Added local task configurations

crates/languages/src/json.rs

@@ -72,7 +72,10 @@ impl JsonLspAdapter {
                         "schema": KeymapFile::generate_json_schema(&action_names),
                     },
                     {
-                        "fileMatch": [schema_file_match(&paths::TASKS)],
+                        "fileMatch": [
+                            schema_file_match(&paths::TASKS),
+                            &*paths::LOCAL_TASKS_RELATIVE_PATH,
+                        ],
                         "schema": tasks_schema,
                     }
                 ]