channel address support

Support for channel address can be implemented in several steps:

• #621
• A new AST element is created, but the codegen will replace its value with 0
• #647
• Regions can be defined as M<Size>, G<Size> or with simply a number
• The M region are locally shared data
• The G region are globally shared data, this region can be defined from the outside
• Numbered regions represent hardware, they can be accessed by either the I or Q symbols (%IX1.2) will access region 1 starting from bit 2
• #648
• A region in the body is simply a pointer access to that region defined by the rules of access (%MX2 is accessing bit 2 of the locally shared data)
• A region accessed in a variable declaration with AT marks that the variable being declared is an auto pointer to that location.

Originally posted by @ghaith in https://github.com/PLC-lang/rusty/issues/621#issuecomment-1313292591

Start with the linked issue #647 for the unfinished region definitions and review the AST and codegen work described for #621, along with the pointer-access behavior completed in #648. Implement the remaining channel address rules for local, global, and hardware regions, including I/Q access, then verify that the regions are represented and accessed according to those rules.