Fix Search bar disappearing on Discover tab when scrolling

[pelumy]

Issues covered

#1679

Description

This PR fixes the Search bar disappearing on Discover tab when scrolling. This is fixed by using the custom SearchBar instead of Apple's .isSearchable modifier.

How to test

1. Navigate to the discover tab.
2. Scroll through the recommended profiles.
3. Please check that the search bar is still visible and doesn't disappear.
4. Go to a different tab and switch back to the discover tab.
5. Please check that the search bar is still visible after switching back.

Screenshots/Video

Before	After

[mplorentz]

👀

[mplorentz]

I'm seeing a few minor issues here:

• Typing a query then tapping clear sometimes results in the loading view being displayed instead of featured authors
• I think the gap between the magnifying glass and placeholder text is too large
• The font in the search bar doesn't look the same as the one in Figma.
  I'm going to take a crack at fixing these since I think you are offline.
• font for query

[mplorentz]

I fixed up the fonts. I ended up using the .placeholder modifier that we already had because it was simpler than adding more parameters to PlaceholderModifier. Let me know what you think! But I'm going to go ahead and merge this so we can get into the App Store review queue!

[pelumy]

Waawu, I didn't know this was existing. This is great @mplorentz

[pelumy]

I love the new approach and I feel it is cleaner. We should change the other place where the modifier was used after the launch. Thanks for fixing this @mplorentz.