Move to OpenAPI 3.1

[karol-kokoszka]

Scylla manager uses code generators to create scylla , scylla-manager-agent, scylla-manager Go clients.
The code is generated out of https://github.com/scylladb/scylla-manager/tree/master/swagger

Specification that is defined here is in Swagger 2.0

scylla-manager/swagger/scylla_v1.json

Line 2 in 6b38cea

"swagger": "2.0",

Clients are generated here https://github.com/scylladb/scylla-manager/blob/master/swagger/Makefile

The reason for that change is the default encoding that happens on parameters.
Alternator allows to use special characters in column names - current client is escaping these characters.

#3754

Goal
Update specifications to use OpenAPI 3.1.
Validate the tools that can be used to generate clients out of OpenAPI 3.1.
Generate new clients.
Update references in Scylla-Manager to use new clients.

[karol-kokoszka]

This issue is triggered by the following problem #3754

[tzach]

Similar issue on Scylla Core scylladb/scylladb#18028