[Feat]: SVG icons for the pmahomme theme #20537

phpMyAdmin version

6.0.0-dev (master)

Describe the feature

The pmahomme theme uses small PNG icons. They look blurry on
high-resolution screens and when the page is zoomed (see #11392).
An earlier attempt to use an SVG sprite (#18789) was reverted because
it did not work correctly on Chromium browsers.

Describe the solution

I replaced all 171 PNG icons of pmahomme with SVG icons. Each icon is
an inline SVG in the theme's CSS (not a sprite), keeps the colours of
the image it replaces and is aligned with the text next to it. I
tested it in Edge (Chromium) and it renders correctly.

Along the way I also made a few small UI improvements to the theme:

• Top menu tabs wrap onto a new row instead of using the "More" menu
• The navigation panel slides in and out with a short animation
• Drop-down lists get a custom picker with an animated arrow
• The login form gets a show/hide password button

Branch: https://github.com/arifkhann5321-art/phpmyadmin/tree/design-update

Would you like me to open a pull request? I'm happy to split it into
smaller ones (for example icons first, then the other UI changes) if
that is easier to review.

Describe the alternatives

Keeping the PNG icons and adding @2x versions for high-resolution
screens, but that doubles the number of image files and still does
not scale for every zoom level.

Additional context

Old vs new icons (old PNG on the left, new SVG on the right):

cc @MauricioFauth since you worked on the SVG sprite.