Disk: ReadDriver: Add unified cache

Previously, we had to copy an entire block out of the
old cache every time we wanted to read even a single
byte from it.

This ended up being a fairly significant performance
issue, in addition to the fact that the caching code
was duplicated.

include/icsneo/disk/plasiondiskreaddriver.h

@@ -24,11 +24,6 @@ public:
 
 private:
 	static constexpr const uint32_t MaxSize = 65024;
-	static constexpr const std::chrono::seconds CacheTime = std::chrono::seconds(1);
-
-	std::array<uint8_t, MaxSize> cache;
-	uint64_t cachePos = 0;
-	std::chrono::time_point<std::chrono::steady_clock> cachedAt;
 
 	Access getPossibleAccess() const override { return Access::EntireCard; }