Reorganize Makie test files

[ffreyer]

Description

I've been thinking for a while that organizing tests into a few folders would be helpful so I did that here.

As of 8e09652:

• This does not change any test that was included before
• This does split up events.jl without any functional changes (1)
• This does change and include tests that were previously not running (zoom_pan.jl, timings.jl). (1) zoom_pan has been merged with the Axis tests from events.jl.
• This does change 3 lines of Makie code - 2 to catch BudgetedTimer callbacks erroring and 1 fixing stop!(timer) being unavailable in WGLMakie (how did this not error before? Does isopen(screen) not become false after closing a WGLMakie screen?)

Type of change

• Test/CI improvements

[MakieBot]

Benchmark Results

SHA: 6dbb2773fb931e8b0e4d599a773e902f000e0cfe

Warning

These results are subject to substantial noise because GitHub's CI runs on shared machines that are not ideally suited for benchmarking.

[ffreyer]

Double checked the number of tests after the last merge, seems correct (54 more than master)