Replace more PNG icons with SVGs

[pavithraes]

General todos:

• issues: fixes Finalize migration from PNG to SVG icons #12282
• tests added / passed
• release document entry (if new feature or API change)

PR-specific todos:

• Update ToggleMode icon
• Update baseline tests

Notes:

• The new icons were exported from Figma and have colors associated with them, but I think the CSS mask will override it and that is what we want for consistency.
• Need to add @smeragoel as co-author on the PR, as the design contributor for new icons
• Icons in documentation still use old png versions, updating these is a little more involved, so I think we can do that in a separate PR: [DOCS] Update docs pages with new SVG icons #14521

[mosc9575]

Sorry for the late review, but since the ToggleMode icon is updated, I think the lines

bokeh/bokehjs/src/less/icons.less

Lines 3 to 6 in 3801f1d

	.tool-icon(@icon, @file) {
	@path: "../../../docs/bokeh/source/_images/icons";
	background-image: var(@icon, data-uri("@{path}/@{file}.png"));
	}

arn't needed anymore. If I am right, they should be deleted to avoid an unnecessary fragment.

[mattpap]

There's more cleanup needed elsewhere as well, that's why I didn't push for doing it in this PR.

[github-actions]

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