Fix missing options in htmlbars-ast-plugin

[FabHof]

This fixes #166

The problem is as follows: When using ember-css-modules in an ember-addon, the options are added in the included function of the ember-addon, and is therefore not available when setupPreprocessorRegistry of ember-css-modules is run. So the htmlbars-ast-plugin did not get the information about virtualModules.

This fix uses a bound function instead of an options object. I don't know anything about the ember-cli API, so there is probably a better solution.

[dfreeman]

Hi @FabHof, thanks for the PR! Unfortunately all configuration for Babel and Glimmer/HTMLBars plugins has to be JSON-serializable in order for the CLI to be able to spin up multiple workers and process files in parallel, so passing through a closure to fetch the needed data later is unfortunately a non-starter.

I'm going to close this out, but I'll write up a suggestion in #166 for a possible workaround. I'm sorry for how long this has taken to get resolved! The chicken-and-egg ordering concerns here have had me running in circles for a while now.