consolidate and reorder tests

When we moved tests into xt/ it left a hole in the numbers. I also
combined two test files and deleted one that is simply skipped (it's
always in the git history if we need it again).
remove dependency on File::Slurp

We were only using it in a test, and there's a way to force FSEvents
using just File::Temp.
explicitly define all dependencies

And remove one that we don't need anymore
add docs about the flags available

A short blurb about the flags so users know what they do. The Apple docs
are a bit hard to navigate when the API presented by this module is so
different.

Fixes #100941
move flags into constructor arguments

In addition to allowing a bitfield of flags, now we allow constructor
args with the flag names. This way, users don't need to import the flag
constants into their package, and they don't have to know how to
construct a bitfield.

Fixes #100940
add note about symbolic links in watched paths

If the watched path is part of a symbolic link, the event path will not
appear to be in the watched path. The event's path will be the real
path.
add watching multiple paths at once

Now we can watch on any number of paths at once, making things a bit
easier and more efficient.

Fixes #100939
upgrade ppport.h

I tried to use av_top_index() like perlapi says I can, but it turns out
this was added in 5.17 and does not work on the 5.12 I tested it on.

ppport.h is the correct way to get new perlapi calls on older perls
remove unnecessary gitignores

No need to ignore these now that tests don't create them.