Pica: Set program code / swizzle data limit to 4096

One of the later commits will enable writing to GS regs.
It turns out that on startup, most games will write 4096 GS program words.

The current limit of 1024 would hence result in 3072 (4096 - 1024) error messages:
```
HW.GPU <Error> video_core/shader/shader.cpp:WriteProgramCode:229: Invalid GS program offset 1024
```

New constants have been introduced to represent these limits.
The swizzle data size has also been raised. This matches the given field sizes of [GPUREG_SH_OPDESCS_INDEX](https://3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_SH_OPDESCS_INDEX) and [GPUREG_SH_CODETRANSFER_INDEX](https://www.3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_SH_CODETRANSFER_INDEX) (12 bit = [0; 4095]).