* fix(rust): discriminator mapping to serde rename
Discriminator mapping has been ignored in some cases.
Even existing samples had wrong definition in some cases
This PR addresses this
* fix(rust): `oneOf` generation for client
Solves #17869 and #17896 and also includes unmerged $17898
Unfortunately it affects quite a lot of code, but we can see that only client-side models were affected by re-generation.
I tried to split this PR to several, but they're really coupled and hard to create a chain of PRs.
* fix: indentation in `impl Default`
* missing fixes
* fix: correct typeDeclaration with unaliased schema
* style: improve indentation for models
* fix: user toModelName for aliases of oneOf
* refactor: unify `getTypeDeclaration` for rust
* cover the case when `mapping` has the same `ref` for different mapping names
* test: add test for previous change
* style: remove extra qualified path to models
* add some comments
* fix(build): use method of `List` instead of specific for `LinkedList`
* fix(rust): simplify None logic
Used to be a code path (where isFreeFormObject and something else) where we could end up with two `: None` `: None`'s
This does add the None for the !required && !isArray && !isMap && !isNullable case (where nothing would have been printed before.
Above for the type on the individual vars inside the struct definition the logic is simply if not required then it's optional.
If it's optional we want a None when creating a new struct.
* ci: add tests for failure
