Add unittest/TestTextureReplacer which creates a fictive texture pack
(textures.ini with readable invented hashes plus real PNG files), loads
it via the replacer, and verifies lookups, filtering, hashranges, mip
levels, and missing/ignored entries.
To make the replacer runnable outside the emulator:
- The constructor now accepts a null DrawContext (formats just default
to unsupported).
- FindReplacement/FindFiltering use the replaceEnabled_ member instead
of the global config.
- Added TextureReplacer::LoadPackForTesting() to load an ini from a
path directly.
