* generator - includes all the functions required to generate code
* context - Stores context structures required for code generation
* result - Stores CodeGenResult and CodeGenError
* utils - all the necessary utilities for code generation

* adds more doc comment changes
* moves properties like annoymous type counter and tera to generator
from context
* context only stores data model property and is locally created for
each ISL type code generation
* adds Template struct which stores information about which templates
are supported and has a method to navogate to a particular template file
for code generation

* Doc comment changes
* rename from `name` to `target_kind_name` for template variable
* Update Result to use `IonSchemaError` instead of `IonError`
* Add newline at the end of each template
* Other variable renaming changes