LibGfx: Add OpenType opcodes and helpers to parse instruction streams

This defines all the OpenType opcodes/instructions from the
specification:
https://learn.microsoft.com/en-us/typography/opentype/spec/tt_instructions

Each instructions has mnemonic and a range of possible opcodes (as some
of the bits are pretty much immediate value flags).

There's a little helper Instruction struct for accessing the flags and
any associated data (in the case of PUSH instructions).

Then the InstructionStream provides a way of iterating over all the
instructions in some bytes.

Userland/Libraries/LibGfx/CMakeLists.txt

@@ -21,6 +21,7 @@ set(SOURCES
     Font/OpenType/Cmap.cpp
     Font/OpenType/Font.cpp
     Font/OpenType/Glyf.cpp
+    Font/OpenType/Hinting/Opcodes.cpp
     Font/PathRasterizer.cpp
     Font/ScaledFont.cpp
     Font/Typeface.cpp