TextureCacheBase::LoadImpl has a hot path where the passed-in
TextureInfo never gets used. Instead of passing in a TextureInfo, let's
pass in the stage and create the TextureInfo from the stage if needed.

This unlocks somewhere above an additional 4% performance boost in the
Hoth level of Rogue Squadron 2 on my PC. Performance varies, making it
difficult for me to measure, so treat this as a very approximate number.

Fix various typos and spelling mistakes

c++23: Replace Common::ToUnderlying with std::to_underlying

The TextureInfo constructor creates a vector of MipLevels. This could be
good for performance if MipLevels are accessed very often for each
TextureInfo, but that's not the case. Dolphin creates thousands of
TextureInfos per second that it never accesses the mipmap levels of
because there's a hit in the texture cache, and in the uncommon case of
a texture cache miss, the mipmap levels only get looped through once.

To make the common case of texture cache hits as fast as possible, let's
not create a vector in the TextureInfo constructor. This commit
implements a custom iterator for MipLevels instead.

In my testing on the Death Star level of Rogue Squadron 2, this speeds
up TextureInfo::FromStage by 200%, giving an overall emulation speedup
of a bit over 1%. Results on the Hoth level are even better, with
TextureInfo::FromStage being close to 300% faster and overall emulation
being over 4% faster. (Single core, no GPU texture decoding.)

Requires at least GCC 11, Clang 13, MSVC 19.30 (VS2022 17.0), or AppleClang 13.1.6 (XCode 13.3).

VideoCommon: Fix "Force Nearest" texture filter setting.