[web] Remove default stroke for wrench icon

Summary:
Without this change, we aren't able to change the color of the wrench icon, which makes styling it on hover, etc impossible.

There was a default stroke color for the wrench icon that couldn't be overridden via CSS... so removing it manually for now to unblock.

We converted stroke/path to object/shape before importing to IcoMoon when we included the icons on native, but I guess didn't for web?

Open to any/all alternative approaches, this is all I could get to work.

Test Plan: NA, able to style the wrench icon

Reviewers: def-au1t, palys-swm, varun, benschac

Reviewed By: palys-swm

Subscribers: ashoat, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3362