Refs #10087
Add validation of all params for the keyspace_scrub api.
The validation method is generic and should be used by all apis eventually,
but I'm leaving that as follow-up work.
While at it, fixed the exception types thrown on invalid `scrub_mode` or `quarantine_mode` values from `std::runtime_error` to `httpd::bad_param_exception` so to generate the `bad_request` http status.
And added unit tests to verify that, and the handling of an unknown parameter.
Test: unit(dev)
DTest: nodetool_additional_test.py::TestNodetool::{test_scrub_with_one_node_expect_data_loss,test_scrub_with_multi_nodes_expect_data_rebuild,test_scrub_sstable_with_invalid_fragment,test_scrub_ks_sstable_with_invalid_fragment,test_scrub_segregate_sstable_with_invalid_fragment,test_scrub_segregate_ks_sstable_with_invalid_fragment}
Closes#10090
* github.com:scylladb/scylla:
api: storage_service: scrub: validate parameters
api: storage_service: refactor parse_tables
api: storage_service: refactor validate_keyspace
test: rest_api: add test_storage_service_keyspace_scrub tests
api: storage_service: scrub: throw httpd::bad_param_exception for invalid param values
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