Add the ability to hide racer avatar display while in a race

[nihonjinrxs]

Closes #133

Add a new boolean user setting hide_avatars_while_racing to enable users to turn off racer avatar display while in a race.

(This PR is still a work in progress.)

[nihonjinrxs]

I posted in Discord about this, but I'll outline the current trouble here too.

I've created a new @property method on the User model that returns a boolean type. (I've tested this and I'm sure that's the case.)

When I use the user partial template (inside the entrant row partial here) with a boolean directly, it behaves as I expect:

<!-- avatar not shown -->
{% include 'racetime/pops/user.html' with user=entrant.user extra_class='inline' 
hide_avatar=True %}

<!-- avatar shown -->
{% include 'racetime/pops/user.html' with user=entrant.user extra_class='inline' hide_avatar=False %}

When I use the new property method, it seems to just ignore it:

<!-- always displays avatars no matter the return value -->
{% include 'racetime/pops/user.html' with user=entrant.user extra_class='inline' hide_avatar=request.user.hide_all_avatars %}

Help appreciated.

[nihonjinrxs]

So with a bit more digging, using this code in the on the entrant row partial, I can see the information passed in that I need for this, but then it seems to get wiped out by the websocket message renders.

        request.user = "{{ request.user.name }}#{{ request.user.discriminator }}"
        user = "{{ user.name }}#{{ user.discriminator }}"
        entrant.user = "{{ entrant.user.name }}#{{ entrant.user.discriminator }}"
        request.user.hide_all_avatars = ({{ request.user.hide_all_avatars }})
        {% include 'racetime/pops/user.html' with user=entrant.user extra_class='inline' hide_avatar=request.user.hide_all_avatars %}

I'm going to look into memoizing that request.user data on page load so that I can make use of it later, irrespective of what comes in on the websocket.