[feature]: Support using system fonts (#304)

* [feature]: Support using system fonts

Uses the **experimental** queryLocalFonts API, when prompted, to get the fonts and do CSS.
Resolves #270 and #288 (by proxy)

Caveats/notes:
- This is experimental, and is only supported by Chrome/Chromium/Edgeium (see https://caniuse.com/?search=querylocalfonts)
- As far as I can tell, the only way to dynamically change the font (shown in https://wicg.github.io/local-font-access/#example-style-with-local-fonts) was by DOM manipulation; css variables did not seem to work
- This shows **all** fonts, including their variants (bold/italic/etc); given that the style names could be localized, not sure of a way to parse this (on my system, for instance, I had 859 different combinations)
- I made fonts a separate top-level setting because it was easier to manipulate without causing as many rerenders; feel free to put that back

* add permission chec

* add electron magic to support custom font

* restrict content types

src/main/preload/local-settings.ts

@@ -1,4 +1,4 @@
-import { ipcRenderer, webFrame } from 'electron';
+import { IpcRendererEvent, ipcRenderer, webFrame } from 'electron';
 import Store from 'electron-store';
 
 const store = new Store();
@@ -39,9 +39,14 @@ const setZoomFactor = (zoomFactor: number) => {
     webFrame.setZoomFactor(zoomFactor / 100);
 };
 
+const fontError = (cb: (event: IpcRendererEvent, file: string) => void) => {
+    ipcRenderer.on('custom-font-error', cb);
+};
+
 export const localSettings = {
     disableMediaKeys,
     enableMediaKeys,
+    fontError,
     get,
     passwordGet,
     passwordRemove,