make vectorized LOWER(), UPPER(), LENGTH() work end-to-end; support expression input for vectorized LIKE

Vectorized expressions have been implemented for UPPER(), LOWER() and LENGTH() for strings but they have not been tied through end-to-end to work in queries. VectorizationContext needs to be updated to do this.

Also, LIKE support in VectorizationContext needs to be extended to support a string function as an input.