Option for Customizing Field Omission

[inoc603]

The new omitzero behavior is very nice, but it can only be defined using tags. Can we introduce a new option to modify the behavior, e.g. treat omitempty as omitzero, so structs imported from another package can be marshaled with the new omitzero behavior？

[dsnet]

I think something like this is reasonable. Probably an option like "OmitZeroStructFields".

[dsnet]

I analyzed all public Go code known by the proxy as of 2024-04-01 for existing json struct tags. This is the number of each combination of tags:

Percent	Count	Tag combination
49.9%	26260569	name,omitempty
44.2%	23290292	name
5.4%	2821440	-
0.3%	136470	,inline
0.2%	114903	,omitempty
0.0%	14071
0.0%	6261	,omitempty,inline
0.0%	266	name,inline
0.0%	115	name,omitzero
0.0%	97	name,omitzero,omitempty
0.0%	68	name,omitempty,inline
0.0%	1	,format

It seems that omitempty or omitzero is present in about half of all fields with an explicit json tag.

EDIT: I removed occurrences within test files.

[dsnet]

#61 adds a caller-specified option to omit all zero struct fields.