Apparently we'd never bothered opting in, despite nearly everything in all out apps being entirely compatible and designed with long paths in mind.
GetModuleFileNameW is a bit awkward as it's just about the only Win32 function that returns the minimum of the buffer size and the string size - nearly everything else returns the full size even if it won't fit, so you can pass it a null pointer and a size of zero, and it'll tell you how much space you need to allocate.
I pretty much just copied the mostly-working long-path-friendly call site in the crash catcher to windowspath.cpp, but I also noticed that if the function failed and returned zero, the original implementation would loop forever, so I fixed that.
There was some code that could be ditched from the catch monitor as \\?\ is a prefix you can use to opt into long paths for a single API call instead of using the manifest to set it everywhere.
Resolves https://gitlab.com/OpenMW/openmw/-/issues/8100
Also removes some old crud.
Hopefully the old crud is all:
* Handled automatically by CMake now we're using the modern approach.
* A hack-fix for a problem caused by not using the modern approach.
* Massively outdated so no longer necessary.
If it turns out this makes CI fail, I'll tweak things as necessary.
Changes that might not be wanted include:
* Getting rid of our BOOST_STATIC CMake option. In cases where the CMake config doesn't make the one correct choice from the build environment (i.e. because there's a choice) the CMake config exposes the option already.
However, we were forcing this on for Windows, so that might matter.
It seems to default to static on my machine even though I thought I read something suggesting otherwise, so we'll see how things go with that.
If we eventually put CMake in charge of installing dependency DLLs this will be a moot point as we won't need to care.
* Bumping the minimum version of Boost to 1.70.0, as that's the first with working CMake config.
It's from 2019, so plausibly there are distros too scared to use a library from five years ago as it can't legally drink in the US (although it could in limited quantities with parental supervision in the UK, as long as it's just something inconsequential like a single sip of beer).
