Add member controls UI for relations (load and select actions)

[Shyam-123pandey]

Vedio of testing:

fixed122.mp4

Add a compact set of controls above the relation members list to support bulk operations.

This introduces actions to:

• load all relation members
• select currently loaded members
• select all members when fully loaded

The "select all" action is disabled when not all members are loaded to avoid partial edits and unexpected behavior.

This change focuses on making bulk operations explicit and safe, instead of relying on implicit keyboard shortcuts.
closes: #12122

[Copilot]

Pull request overview

Adds a compact “member controls” button group intended to make bulk operations on relation members explicit (load/select), addressing #12122.

Changes:

• Added a new controls row (load/select actions) above the membership list UI.
• Introduced styling for the new controls in a dedicated CSS file.
• Minor formatting/style tweak in modeSelect keybinding chaining.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 8 comments.

File	Description
modules/ui/sections/raw_membership_editor.js	Adds functions and UI controls to load/select relation members from the membership editor panel.
modules/modes/select.js	Small keybinding chain formatting change.
css/raw_membership_editor.css	Adds styles for the new member controls button group.

[Shyam-123pandey]

All suggestion will fix tomorrow, will do updated commit. thanks

[Shyam-123pandey]

Now all test have been passed, will do next commit shortly.
thanks