Uniform parsing of expressions

We have ran in to some issues where templates expressions are sensitive to the params.
for example specifying true vs 'true'.

We should solution for a consistent experience for using the expressions in the templates, and increase the friendliness of using and contributing to them.

Start by locating the template expression parsing entry point and reproduce the difference between true and 'true'. Define the consistent behavior for template expressions, then verify that equivalent parameter forms are handled consistently; the issue names no files or tests.

Written by the indexing model from the issue text.