Update tooling for HTMLBars compiler/syntax package split.
Attributes are previously concatted, do not concat again.
Move concat into hooks module
Use AST builders in each/with transforms
Switch attribute bindings to diffing strategy
Bump HTMLBars version to 0.4.0.
Remove ConcatAttrNode.
Merge pull request #9817 from emberjs/update-htmlbars-part-500000

Update HTMLBars to 0.4.0.