Set base for settings, add volatile settings for theme and language

Goal is to have a common and reusable base for the settings. Having nice styles and saving preferences is out of scope for now.

Note the conversation page is now the "main page" instead of the account settings.

Change-Id: I328686047d924642ae6781096c9f57308e8fea22
diff --git a/client/src/components/Header.tsx b/client/src/components/Header.tsx
index 8373601..64d4c12 100644
--- a/client/src/components/Header.tsx
+++ b/client/src/components/Header.tsx
@@ -36,11 +36,12 @@
   return (
     <Box>
       <Button aria-controls="simple-menu" aria-haspopup="true" onClick={handleClick}>
-        Menu
+        {t('Menu')}
       </Button>
       <Menu id="simple-menu" anchorEl={anchorEl} open={Boolean(anchorEl)} onClose={handleClose}>
         <MenuItem onClick={goToContacts}>Contacts</MenuItem>
-        <MenuItem onClick={() => navigate('/settings')}>Account settings</MenuItem>
+        <MenuItem onClick={() => navigate('/settings-account')}>{t('settings_account')}</MenuItem>
+        <MenuItem onClick={() => navigate('/settings-general')}>{t('settings_general')}</MenuItem>
         <MenuItem onClick={logout}>{t('logout')}</MenuItem>
       </Menu>
     </Box>