Migrate spec/javascripts/behaviors/ to Jest

Description

Let's migrate the specs in spec/javascripts/behaviors/ from Karma to Jest.

See the related epic for how to do this.

• spec/javascripts/behaviors/quick_submit_spec.js !25934 (merged)
• spec/javascripts/behaviors/markdown/highlight_current_user_spec.js !33975 (merged)
• spec/javascripts/behaviors/gl_emoji/unicode_support_map_spec.js !33975 (merged)
• spec/javascripts/behaviors/autosize_spec.js !33975 (merged)
• spec/javascripts/behaviors/shortcuts/shortcuts_issuable_spec.js !33975 (merged)
• spec/javascripts/behaviors/copy_as_gfm_spec.js !33975 (merged)
• spec/javascripts/behaviors/requires_input_spec.js !33975 (merged)