add new fields and update examples

[modular-magician]

Release Note Template for Downstream PRs (will be copied)

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discoveryengine: added `connector_modes`, `sync_mode`, `incremental_refresh_interval`, `auto_run_disabled`, and `incremental_sync_disabled` fields to `google_discovery_engine_data_connector` resource

discoveryengine: added `kms_key_name` field to `google_discovery_engine_search_engine` resource

discoveryengine: fixed bug where it wasn't possible to specify values for `knowledgeBaseSysId` or `catalogSysId` in `google_discovery_engine_data_connector.entities.params`.

discoveryengine: changed type of `google_discovery_engine_data_connector.entities.params`. Previously, it was a map of string keys to string values; now, it must be a [JSON-encoded](https://developer.hashicorp.com/terraform/language/functions/jsonencode) string containing an object. This change is being made in a minor release because the field wasn't usable as intended – specifically, all current valid uses require mapping strings to _lists_ of strings.

Derived from GoogleCloudPlatform/magic-modules#15296

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