Canvas Link uitility components

[seanrcollings]

Add a set of link utility components in @atomicjolt/canvas-client for linking to content in Canvas

• CanvasLink - Generic component. Wrapper around Link. Accepts a path and defaults to opening in a new tab
• CanvasCourseLink - accepts a courseId
• CanvasAssignmentLink - accepts a courseId and assignmentId

etc...

As part of this, implement a CanvasProvider Context provider for providing information about the canvas instance (such as the domain)