libkernel: Various filesystem fixes (#2868)

* Proper handling of whence 3 & 4

* Accurate directory handling in open

Directories can be opened, and can be created in open, these changes should handle that more accurately.

* Mount /app0 as read only

On real hardware, it's read only.

* Proper directory flag handling.

Even when directory is specified, it will still succeed to open non-directories.

* Check for read only directories

* Earlier ro check in posix_rmdir

Hardware tests suggest these checks are in a different order

* Clear temp folder on boot

My tests rely on this, and some games do too.
Two birds with one stone

* Clang

* Add missing DeleteHandle calls

Whoops

* Final flags adjustment in sceKernelOpen

All my current tests are now hardware accurate.

* Fix truncates

Host ftruncate consistently fails on EINVAL, I'll need to test if this issue affected Windows too.

* Windows hacks

Windows is more limiting about how folders are opened and things like that. For now, pretend these calls didn't error.
Also fixes compilation for Windows

* Final touch-ups

After expanding my test suite further, I found a couple more edge cases that needed addressing.
Bloodborne audio is still broken, I'll look into that soon.

* Remove hacky read-only behavior in posix_stat

Bloodborne apparently uses the mode parameter here when querying it's audio files, and the mode we returned led to it disabling audio entirely.

* Clang

* Cleaner code

* Combine fsync and sync flags

According to FreeBSD docs, the "sync" flag is synonymous with the fsync flag, and is only included to meet the POSIX spec.

* Log if any currently unhandled flags are encountered.

These are rare and probably not too important, but log a warning when they're seen.

* Update file_system.cpp

* Update file_system.cpp

* Clang

* Revert truncate fix

Using ftruncate works fine after moving the call to before the proper file opening code.

* Truncate before open

Open the file as read-write, then try truncating.
This fixes read | truncate flag behavior on Windows.

* Slightly adjust check for invalid flags

Any open call with invalid flags should return EINVAL, regardless of other errors parameters might cause.

src/common/io_file.h

@@ -61,8 +61,6 @@ enum class SeekOrigin : u32 {
     SetOrigin,       // Seeks from the start of the file.
     CurrentPosition, // Seeks from the current file pointer position.
     End,             // Seeks from the end of the file.
-    SeekHole,        // Seeks from the start of the next hole in the file.
-    SeekData,        // Seeks from the start of the next non-hole region in the file.
 };
 
 class IOFile final {