Allow all keyboard interactions on select component

The gg-select component replaces the <select> component. Its main purpose, however, is to replace the use-case of <select multiple> to select more than one option at a time.

Right now, users can’t interact with the select component when using the keyboard. Jumping to it via Tab works but not opening it. The behavior to use it with a keyboard should be similar to Salesforce’s combobox.