Make the export buttons 'better'

Problem/Motivation

There are many tickets in the queue all essentially running up against the same thing: the default export buttons are rubbish.

These tickets are:

• ✨ Make the export button text configurable Active
• ✨ Provide better download button style Active
• ✨ Export Button, make it styleable with CSS Needs work
• #3249028: Change download button name to Export Results →
• ✨ Add export links as local actions instead of feed icons Active
• #2943895: Make export link configurable (text and options) →

And there may be others!

In summary:

• Some users of the module are fine with the buttons as they are
• Some users of the module don't want the buttons at all, but would like local actions
• Some users of the module want to be able to customise the text of the button
• Some users of the module want to be able style the button with CSS in a nice way
• Some users of the module just want it to look like a normal link/button in Drupal's default admin theme
• Solving this piecemeal isn't going to get us anywhere

Proposed resolution

We should work to making the export buttons be configurable in some way, so that you can:

• Pick from various 'styles' of button, and we can include the current styling as a 'legacy' option.
• For where it makes sense for a style, offer as much customisation as is reasonable, i.e. allowing someone to customise the text of a download button etc.
• See if we can offer button placement top/bottom type options, though I rather suspect that's a views theming issue.
• Attempt to get local actions stuff working, but I suspect that'll be incredibly tricky to get working correctly.

Remaining tasks

Code up the new solution, including tests for it where appropriate, and release it asap!

User interface changes

TBC

API changes

TBC

Data model changes

TBC