Keybinds for moving line anchors to start/end of system

[XiaoMigros]

Resolves: #23307

• I signed the CLA
• The title of the PR describes the problem it addresses
• Each commit's message describes its purpose and effects, and references the issue it resolves
• If changes are extensive, there is a sequence of easily reviewable commits
• The code in the PR follows the coding rules
• There are no unnecessary changes
• The code compiles and runs on my machine, preferably after each commit individually
• I created a unit test or vtest to verify the changes I made (if applicable)

[zacjansheski]

Apologies for letting this get dusty! Let's circle back to this after #28916 is fixed

[zacjansheski]

@XiaoMigros would you mind giving this a rebase and I'll take a look?

[zacjansheski]

Tested on MacOS 15, Windows 11, Ubuntu 22.04.3. Approved
#23307 FIXED