feat(source-location): add LocationSource for push-based location context

Implements FeedSource interface. Accepts external location pushes,
provides context to downstream sources, does not produce feed items.

Supports configurable history size.

Co-authored-by: Ona <no-reply@ona.com>

packages/aris-source-location/src/index.ts

@@ -0,0 +1,6 @@
+export {
+	LocationSource,
+	LocationKey,
+	type Location,
+	type LocationSourceOptions,
+} from "./location-source.ts"