Fixes regression by 761206cf, causing
yuzu to not build on Linux with any version of Boost except a cached
1.73 Conan version from before about a day ago.

Moves the Boost requirement out of the `REQUIRED_LIBS` psuedo-2D-array
for Conan to instead be manually configured, using Conan as a fallback
solution if the system does not meet our requirements.

Requires any update from the linux-fresh container in order to build.

**DO NOT MERGE** until someone with the MSVC toolchain can verify this
works there, too.

vfs: Use existing type aliases consistently

fs: Revert all std::filesystem changes

svc: Remove unnecessary casts

This reverts commit ce5fcb6b, reversing
changes made to 6f417630.

This reverts commit 5fe55b16, reversing
changes made to e94dd7e2.

This reverts commit 6d611547, reversing
changes made to 5fe55b16.

This reverts commit 4e94d0d5, reversing
changes made to 6d611547.

This reverts commit cdb36aef, reversing
changes made to 5e9b7712.

common/file_util: Address review comments of #5174

travis/linux: Use correct ccache directory

nim: Stub IsLargeResourceAvailable

Changes the bound ccache directory to `/home/yuzu/.ccache` instead of
`/root/.ccache`, since the `/root` directory is not accessible by the
`yuzu` user in the guest container.

gl_shader_decompiler: Elide unnecessary copies within DeclareConstantBuffers()

Makes use of the VirtualDir and VirtualFile aliases across the board
instead of having a few isolated places that don't use it.

common/file_util: Let std::filesystem cast from UTF16 to std::string

Fix invalid encoding paths when iterating over a directory on Windows.

vfs_real: Fix CreateFile for files without a file extension

common/file_util: Fix and deprecate CreateFullPath, add CreateDirs

Fix CreateFullPath to have its intended previous behavior (whatever
that was), and deprecate it in favor of the new CreateDirs function.

Unlike CreateDir, CreateDirs is marked as [[nodiscard]] to avoid new
code ignoring its result value.

network, sockets: Replace `POLL_IN`, `POLL_OUT`, etc. constants with an `enum class PollEvents`

common/file_util: Make use of std::filesystem

Converts creation and deletion functions over to std::filesystem,
simplifying our file-handling code.

Notably with this, CopyDir will now function on Windows.

core: Remove unnecessary enum casts in log calls

applets: Resolve variable shadowing

Greatly simplifies our file-handling code for these functions.

Simplifies and removes some casts. In all cases, these were generally
widening from a 32-bit unsigned type to a 64-bit unsigned type, so no
information would be lost from the conversion.

ci: Remove `-DYUZU_USE_BUNDLED_UNICORN=ON`

Unicorn has been removed, yet CI still enables building with Unicorn.
This just cleans up a few leftovers by removing the variable from the
CMake parameters in CI.

memory: Resolve -Wdocumentation warning for Write()

Write() doesn't return anything, so the @returns tag shouldn't be
present.

configure_motion_touch: Fix unescaped backslash in regex

controller: Avoid unnecessary copies in ConfigurationComplete()

Follows the video core PR. fmt doesn't require casts for enum classes
anymore, so we can remove quite a few casts.

Avoids unnecessary copies.

Avoids unnecessary 1072 byte copies when querying info about
controllers.