Support dots in glimmer component names

[wmlele]

Primitive? attempt, looks ok for my purpose.

[kjhangiani]

the test should actually return <comp.name @value1={{foo}}/> rather than <comp.name @value1={{foo}}></comp.name> since its not used in a block context - will need to support both block and non-block contextual components

[wmlele]

I agree, and l believe that is the subject of #338. Unfortunately that seems to be less trivial to fix than this.