Have a shortcut/command to toggle sticky selection

Description of the problem or steps to reproduce

New feature : Have a shortcut/command to toggle sticky selection.

Specifications

When you activate the sticky selection, you mark the current position of the cursor and when you move the cursor, it selects from your marked position to your current cursor position.
It is like the shift is hold (without holding shift of course) until the deactivate it or you execute a command like copy / cut / delete.

It is named Toggle Sticky Selection in intellij and set mark command in emacs (https://www.gnu.org/software/emacs/manual/html_node/emacs/Setting-Mark.html) and ToggleNormalSelection in alacritty visual mode.

It should be great to have this feature in micro.

Don't hesitate if it is not clear or need more precision.

Thanks for your amazing terminal editor.

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The issue names no files, tests, or entry points. Start by clarifying the exact activation, deactivation, and copy/cut/delete behavior, then trace micro's command and selection handling. Done means a shortcut or command toggles the marked cursor position and selects as the cursor moves, with the specified commands ending the mode.