9.0.1 fixes (#8505) (#8506)

* Fix NRE in `GetAliasResponse`

* Regenerate client

Co-authored-by: Florian Bernd <git@flobernd.de>

Address 9.0-preview feedback (#8497)

Release 9.0 (#8485) (#8491)

Co-authored-by: Florian Bernd <git@flobernd.de>

Fix serialization of `Names` (#8486) (#8487)

Co-authored-by: Florian Bernd <git@flobernd.de>

Regenerate client using the latest specification (#8476) (#8477)

Co-authored-by: Florian Bernd <git@flobernd.de>

Regenerate client using the latest specification (#8472)

* Regenerate client using the latest specification

* Update `Elastic.Transport` to `0.5.9`

Fix potential ArgumentException with ConditionalWeakTable (#8444)

Regenerate client using the latest specification (#8440) (#8442)

Co-authored-by: Florian Bernd <git@flobernd.de>

Regenerate client using the latest specification (#8440) (#8441)

Co-authored-by: Florian Bernd <git@flobernd.de>

Fix `RequestConfiguration` (#8426) (#8428)

Co-authored-by: Florian Bernd <git@flobernd.de>