[HW][SV] Use FieldID in HW/SV dialects

FieldID is very useful feature to specify the subelement in aggregate types(struct, array...). Currently it is supported only in FIRRTL dialect:
https://github.com/llvm/circt/blob/769181bdfd191c4a684301c02e1d43fd7e79bcc6/include/circt/Dialect/FIRRTL/FIRRTLTypes.h#L290-L304

Currently we are using an inefficient implementation to construct an access path from fieldID in ExportVerilog. So we have to replace the implementation once HW/SV dialects support fieldID utilities.

Start with the FieldID utilities in include/circt/Dialect/FIRRTL/FIRRTLTypes.h and inspect the current access-path construction in ExportVerilog. Determine where equivalent FieldID support belongs in the HW and SV dialects, then replace the inefficient ExportVerilog implementation. Done means HW/SV dialects support the needed FieldID utilities and ExportVerilog uses them.

Written by the indexing model from the issue text.