BannerComment should be set by using js2ts cli

[Kruptein]

The json-schema-to-typescript cli already offers a flag to configure the bannerComment, which I assumed would be used by this project.

However specifying a custom bannerComment by doing something like poetry run pydantic2ts --json2ts-cmd "./node_modules/.bin/json2ts --bannerComment='sample banner'" did not replace the banner as anticipated, but instead adds it below the pydantic banner.

Context: The tslint-ignore line is making my eslint very unhappy, this is removed in py2ts (although not yet released) and I hoped to manually set a banner without the tslint line.

Alternatively allowing the option to be set with pydantic2ts cli flags as requested in #16 would also work for me.