provide DGGRIDv8 and support its hierarchy indexing system

[fmigneault]

Description

• Provides access to additional DGGRIDv8 options to output IDs with a different indexing system.
• Provides separate classes for DGGRIDv7 and DGGRIDv8 with their respective properties validated dynamically.

References

• fixes Towards DGGRID version 9 #18
• relates to IGEO7 and Z-indexes specialised functions #17
• relates to How to produce Z7 hex64 indices? sahrk/DGGRID#92

Example invocations with the added functionality:

Input parameters provided for IGEO7 / ISEA7H+Z7 hierarchical indexes:

Results applied by the underlying DGGRID binary call:

Resulting cells contain the expected name of the ZoneID for the requested representation

(previously, the default GLOBAL_SEQUENCE would be applied)

[fmigneault]

@allixender FYI