Add additional helper functions to allow the ability to set Capabilities on TemplateOptions

[aiyengar2]

To test things like this, users should be able to provide Capabilities in TemplateOptions.

While this is already supported today in TemplateOptions, additional helper functions that would allow users to set it following the established pattern in the examples would be helpful:

https://github.com/aiyengar2/hull/blob/33cf243dca452b3fa1d5d471d6bcd6806e2f4205/examples/example_test.go#L57-L58