Linearized composed api

[andreaTP]

Flattened out the OpenAPI description, now anything that starts "With" contains properties, and everything else is a composition of those things.

Description

This change makes it easier for code generators to deal with the spec, both Kiota and OpenApi generator (Go server) are now behaving well.
Like before, even in this solution, there is no repetition of properties.
Please note that the Go Server generated code is completely compatible with the previous one.

How Has This Been Tested?

Tests in CI.

Merge criteria:

• The commits and have meaningful messages; the author will squash them after approval or will ask to merge with squash.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

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[tarilabs]

I have contributed coordination with team and @andreaTP on this topic, this linearization of the openapi as Andrea mentions not only make it easier to be consumed by code-generators, but in the experience it's also easy to manage, while preserving the original principle of DRY: as can be seen in the generated Go model files, structure is preserved.

/lgtm

I only wish there was a prow command for special appreciation too :)

[google-oss-prow]

New changes are detected. LGTM label has been removed.

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: andreaTP
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[tarilabs]

I'm going to hold this one a bit more as I've requested specific feedback, also in relation to:

• Multiple colliding allOfs causing issues in generation microsoft/kiota#4325
• Incorrect merging of model classes microsoft/kiota#4428

/hold