More deprecations and several fixes for v1.5.1

[hemidactylus]

v. 1.5.1
========
Switching to endpoint as the only/primary way of specifying databases:
    - AstraDBClient tolerates (deprecated, removal in 2.0) id[/region] in get_database
    - (internal-use constructors and utilities only accept API Endpoint)
    - AstraDBAdmin is the only place where id[/region] will remain an allowed path in 2.0
    - all tests adapted to reflect this simplification
Admins: resilience against DevOps responses omitting 'keyspace'/'keyspaces'
AstraDBAdmin: added filters and automatic pagination to [async_]list_databases
Consistent handling of deletedCount=-1 from the API (always returned as-is)
Cursors: alignment and rework
    - states are an enum; state names reworked for clarity (better cursor `__repr__`)
    - _copy and _to_sync methods always return a clean pristine cursor
    - "retrieved" property deprecated (removal 2.0). Use `consumed`.
    - "collection" property deprecated (removal 2.0). Use `data_source`.
Deprecation of all `set_caller` (=> to be set at constructor-time) (removal in 2.0)
Callers and user-agent string:
    - remove RAGStack automatic detection
    - Deprecate caller_name/caller_version parameters in favour of "callers" pair list
    - (minor) breaking change: passing only one of caller_name/caller_version to _copy/with_options will override the whole one-item callers pair list
Repo housekeeping
    - using ruff for imports and formatting (instead of isort+black) by @cbornet
    - add ruff rules UP(pyupgrade) by @cbornet
    - remove `cassio` unused dependency