Offer a new full-app embedding url param for logo

[cdeweyx]

Context

We offer several several url parameters for customers in full-app embedding to configure how their Metabase instance looks in the embedded iFrame. We recently made the top_nav default visible and added breadcrumbs as an option in #26977.

With this new behavior, there's a new twist of "I want breadcrumbs so that my users can navigate the instance, but I already show a logo in my app, so having the logo in the top nav as well is duplicative and looks bad." Example below.

Let's offer a new logo sub-param for top_nav that is default on. When it's disabled, breadcrumbs should be scooted over to be left-aligned. Same logic as before if all sub-params are disabled, the whole top-nav is disabled as it serves no purpose.

[bunnymatt]

We got creative and changed the logo to be the sidebar icon :)

[brunobergher]

Here's the spec we agreed to on Slack.

Param
The parameter is called logo, default true.

States
If logo: true and sidenav: true, it looks like regular Metabase
If logo: true and sidenav: false, just don’t show the sidenav hover icon on the logo.
If logo: false and sidenav: true, we always show the sidenav icon, as in the comment above, with the usual gray color in normal state, brand color on hover.
If logo: false and sidenav: false, the breadcrumbs move all the way to the left.