[Frontend] Add explicit Roboto font import

The font was loaded from google servers before.

Author: santeri0200

services/frontend/package-lock.json

@@ -11,6 +11,7 @@
   "dependencies": {
     "@emotion/react": "^11.14.0",
     "@emotion/styled": "^11.14.0",
+    "@fontsource/roboto": "^5.2.8",
     "@mui/icons-material": "^6.4.12",
     "@mui/material": "^6.4.12",
     "@mui/x-date-pickers": "^7.29.4",

services/frontend/package.json

@@ -9,8 +9,12 @@ import purple from '@mui/material/colors/purple'
 import red from '@mui/material/colors/red'
 
 import createTheme from '@mui/material/styles/createTheme'
+import '@fontsource/roboto'
 
 const baseTheme = {
+  typography: {
+    fontFamily: '"Roboto", "Helvetica", "Arial", sans-serif',
+  },
   palette: {
     success: { main: '#03cc0d' },
     disabled: { main: '#9e9e9e' },