Add placeholder text into select2 input in menus

[humancompanion]

In usability testing we noticed that users were not noticing the text input that the select2 plugin provides. The idea here is to add placeholder text in the input so that once the menu is opened some text will be present that will hopefully draw some attention. This will probably need to be hacked into place using JS on top of the plugin.

[bmcorum]

@humancompanion select2 has a placeholder option that continues to display even after focus. https://select2.org/placeholders

[humancompanion]

@bmcorum - Yes, but that's not the input I'm targeting. Those placeholder options are for the menu itself. But, after the menu is opened it shows an input field for the typeahead. Users who don't notice that field start scrolling. We noticed a few users scroll, scroll, and scroll and then give up. They didn't realize the text input for type-ahead was there. So this issue is to add placeholder text to indicate that the "box", because visually it doesn't perhaps read as a text input given its placement, is in fact an input field where they can type.