Create and add icons to Scripts Editor scripts panel context menu items

[ev13bird]

Rework of #97306. I've split up the work into individual PRs for a simpler merging process.

For accessibility purposes and consistency with the Scene dock's node context menu, this PR adds icons to the Scripts Editor's scripts panel context menu:

Some menu items do not have existing appropriate icons, so this PR also adds several new icons:

• SaveAs.svg
• SidePanel.svg
• HelpClose.svg
• ListCloseAll.svg
• ListCloseOthers.svg

I've tried following the documentation's guidelines on creating new icons, but please do feel free to suggest improvements!

[timothyqiu]

My opinion is the same as before: having icons for every menu item is overcrowded. It also weakens the ability to quickly locate menu items by their icons. It would be better to have icons only for representative (frequently used) menu items.

[ev13bird]

Thanks for the suggestion! Which icons do you think should be kept vs removed? I believe @KoBeWi suggested filling more of them out, but I can see it being too overcrowded as well.

[timothyqiu]

Which icons do you think should be kept vs removed?

For example, I think that

• groups like Save* and Close* only needs to have one icon, and
• not frequently used items don't need to have an icon.

[ev13bird]

Fixed, thank you!