Add tests for invalidation fixes

[rikhuijzer]

Invalidation fixes to Julia base are currently not tested. For example:

• fix invalidations from loading Static.jl #46761
• Fixed inference on String and Symbol causing invalidations in show.jl #44091
• Fix ~370 invalidations from Expr(:ncat, ...) pretty-printing #41877

This is asking for double work in the long run. Would it be possible to add something like SnoopCompileCore.@snoopr to Julia base? This would make it easier to add a tests. For example, #46481 fixes invalidations caused by inserting:

Base.:(!)(::True) = False()

With @snoopr defined as

https://github.com/timholy/SnoopCompile.jl/blob/f4d9a7b57a82c1bdb34579f255d3cf4abcc10b92/SnoopCompileCore/src/snoopr.jl#L26-L35

the method insertion could be tested with:

@test isempty(@snoopr Base.:(!)(::True) = False())

cc: @timholy, @ranocha

[ranocha]

Something like this sounds reasonable to me. However, we need to be aware that something like this will still trigger some invalidations, so we could only check some upper bound (that may be increased if required).