Inconsistent behavior of conditions involving `boolean` parameters

Template engine has 4 different expressions evaluators at the moment:
- `CPP` - used for majority of language files
- `CPP2` - used for conditions inside template.json, not used in content generation.
- `MSBuild` - used for conditions in MSBuild files
- `VB` - used for conditions in VB

They act very differently when different syntax is used.

Details:
Given `boolean` parameter `A`
- `CPP2` can process any of those syntax: `if (A)`, `if (A == true)`, `(A == "true")`.
- `CPP` can process those syntax: `if (A)`, `if (A == true)`, but not `(A == "true")`.
- `VB` can process only `if (A)` correctly
- MSBuild can process `if (A)`, `if (A == true)`, `(A == 'true')`, but not `(A == "true")`.

Note MSBuild has 2 ways to define condition as explained [here] (https://github.com/dotnet/templating/wiki/Conditional-processing-and-comment-syntax#msbuild-files).

See https://github.com/dotnet/templating/pull/5800 for more details.
Consider unifying experience, and documenting it better.