feat: Add typing for glint

[muziejus]

This commit adds two files that can be read by Ember apps using glint so that they can benefit from glint's type-checking.

I think I have included all of the possible named attributes that can get passed to the {{svg-jar}} helper.

To wit:

interface SvgJarAttrs {
  width?: string;
  height?: string;
  class?: string;
  role?: string;
  title?: string;
  desc?: string;
}