Simplify app when viewing tangletrees

[joverlee521]

Context

Initially brought up by @jameshadfield in #1924 (comment) and +1 from @huddlej in Slack

I've come to the opinion that we should drop a lot of functionality when viewing two trees, so that if the second tree is displayed we don't allow measurements, frequencies, map to be displayed.

The hope is that disabling all panels except the tree panel when viewing tangletrees will simplify the logic in the app, but unclear if this is true until we dig into it...