Faster horizontal scrolling

[LangLangBart]

Is your feature request related to a problem? Please describe.
Horizontal scrolling with ← / → in a diff is a tad slow.

Important

GIF speed: 2x (for a faster demo)

Describe the solution you'd like
Allow the use of Home and End keys for horizontal movement, similar to how PgUp and PgDn are used for vertical movements.

Gitui	Full-Sized Keyboard	MacBook	Description
❌	Home	fn + ←	takes you to the beginning of a line
❌	End	fn + →	takes you to the end of a line
✅	PgUp	fn + ↑	takes you to the top of the page
✅	PgDn	fn + ↓	takes you to the bottom of the page

Describe alternatives you've considered
I noticed that holding down the ↑ / ↓ keys in the Log [2] viewer accelerates the movement after a few seconds. This could be a useful alternative for holding ← / → in a diff.

Additional context

• the idea to use PgUp / PgDn was conceived in Navigation improvement #1447
• horizontally scrolling a diff came with PR Allow to scroll diffs horizontally #1327