convert toolbar icons to svg

[jkup]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Fix #4852

Still a work in progress, finishing up right now. I messed something up in git and had to open a new PR!

Test Plan:

[bbondy]

++