docs: Fix symbol linking + Pointer docs improvements (excaliburjs#2928)

Closes #

## Changes:

- fix: symbol link handling namespaces/fully qualified symbols
- docs: Better Mouse and Touch (formerly, "Pointers") docs using Twoslash snippets and updated for new API

site/docs/02-fundamentals/04-cameras.mdx

@@ -95,7 +95,7 @@ in-game effects.
 
 "Lerp" is short for [Linear Interpolation](http://en.wikipedia.org/wiki/Linear_interpolation)
 and it enables the camera focus to move smoothly between two points using timing functions.
-Use [[Camera.move]] to ease to a specific point using a provided [[EasingFunction]].
+Use [[Camera.move]] to ease to a specific point using a provided [[Util.EasingFunction|EasingFunction]].
 
 ```typescript
 export interface EasingFunction {

site/docs/05-entity-component-system/05-entity-component-system.mdx

@@ -26,7 +26,7 @@ pieces live and can interact together. Each [[Scene]] in Excalibur contains an E
 
 Inside an ECS [[World]] there is an [[EntityManager]], [[QueryManager]], and [[SystemManager]] that handle all the details.
 
-- [[EntityManager]] - Manages all the entities known by the world, it is an [[Observer]] of entity component changes over time.
+- [[EntityManager]] - Manages all the entities known by the world, it is an [[Util.Observer|Observer]] of entity component changes over time.
 - [[QueryManager]] - Manages all the entity queries, a [[Query]] allows a search of all known entities by a set of component types.
 - [[SystemManager]] - Manages all the systems known by the world, it updates a [[System]] in priority order (low to high) and gives them a set of entities that match types.
 

site/docs/10-physics/08-colliders.mdx

@@ -7,7 +7,7 @@ section: Physics
 Colliders are abstractions over geometry in Excalibur, they implement the [[Collider]] interface and know how
 to detect intersecions with other colliders, test ray casts, check point containment, etc. Related but not the same are [bodies](/docs/bodies) which are abstractions over the collision response
 
-Colliders attached to an [[Entity]] will have a [[Entity.owner]] populated.
+Colliders attached to an [[Entity]] will have a [[Component.owner|owner]] populated.
 
 :::note