Remove AvoidNestedProperties rule

[lmazuel]

It has been discussed in archboard on 12/11, that the SDK team wants to stop supporting model flattening in SDK.

It used to be a pattern we suggested in the past, and therefore we have this rule "AvoidNestedProperties" that could complain if x-ms-client-flatten is not used in some scenarios.

This issue is about removing the rule, since this is in contradiction with new guidance to not use it.

Ideally, we get this rule by 1/5/2024, as TypeSpec will released an update to the Swagger generator to stop using x-ms-client-flatten, and with this rule on every TypeSpec issue will trigger the linter.

[mikeharder]

@AkhilaIlla: Would you be able to remove this rule and push a new release by 1/5/24?

I beleive the rule was added in #384.

[rkmanda]

This rule is not owned by the ARM team. We dont really have an opinion on client flattening as thats an SDK construct. So, whoever on the SDK team owns the SDK related linter rules can feel free to remove these rules. If you cant find an owner, we can add this to our backlog to help cleanup. Please let us know.

[mikeharder]

@rkmanda: Thanks for clarifying, Azure SDK will take ownership of this rule, for both design and implementation.

I noticed this rule is in the "common" ruleset, which is used by both ARM and data-plane:

azure-openapi-validator/packages/rulesets/src/spectral/az-common.ts

Line 479 in 8058c85

AvoidNestedProperties: {

For rules in this "common" ruleset, I propose we assign primary ownership based on which team (ARM or Azure SDK) made the last meaningful change to the rule source code, based on git blame.

@rkmanda, @konrad-jamrozik: Agreed?