[REQ][webclient] Use of extension x-webclient-return-except-except-list-of-string

Is your feature request related to a problem? Please describe.

In this PR, a bug with string arrays for webclient was fixed but in my opinion I think the resolution is not complete/optimal.

It is a breaking change and to maintain backwards compatibility you would have to add the x-webclient-return-except-except-list-of-string extension to each operation in each API.

• We have a large number of apis and operations so we would have to add the extension one by one.

• In my opinion, a particular extension of a technology (webclient) should not be in an API contract. API's should be technology agnostic as one API can be consumed by n technologies.

Describe the solution you'd like

@wing328 I think the ideal would be in the configuration to create a global property to set the behaviour

Start by reviewing PR #16326 and the current handling of the x-webclient-return-except-except-list-of-string extension. Trace how generator configuration reaches webclient operations, then define a global setting that preserves backwards compatibility without requiring per-operation extensions. Done means the behavior can be selected globally and existing API contracts remain technology agnostic.