feat: add sys.query_context_parameters system table

[FrankChen021]

Description

Stacked on apache#20556. Adds sys.query_context_parameters, which lists the query context parameters users can set, built from the QueryContextParameters catalog. INTERNAL parameters are excluded. Descriptions are normalized to one line when the descriptor is built; an enum's description lists its accepted values.

Column	Type
name, type, range, default_value, effective_value, effective_source, default_description, description, visibility, since, deprecation_message	VARCHAR
query_languages (SQL, JSON), engines, native_query_types, statement_types	ARRAY
is_nullable, is_deprecated	BIGINT

default_value is the built-in default. effective_value is the default this Broker applies when a query doesn't set the parameter: the Broker dynamic configuration's queryContext, else the druid.query.default.context.<name> runtime property, else the built-in default; effective_source says which. A null in the dynamic configuration unsets the key, so the built-in default applies. QueryConfigProvider gains getDynamicContext() so the table can tell the dynamic overrides apart.

Unlike sys.servers, the table doesn't require STATE READ: any user who can query sys tables can read the catalog. Only the effective defaults come from Broker configuration, so without READ on the CONFIG resource the query still succeeds, but effective_value is null and effective_source is UNAUTHORIZED in every row.

native_query_types and statement_types are empty when a parameter applies to all native query types or statement types, and null when it doesn't apply to native queries or SQL at all.

The web console's SQL editor now loads the public parameters from this table and suggests them after SET, with each parameter's type, description, default and deprecation in the completion popup. Without CONFIG read access it shows the built-in default and notes that the Broker may override it. If the table can't be read (an older Druid), it falls back to the previous fixed list.

CloneQueryMode now serializes by its JSON name (excludeClones), the same fix as apache#20557, so its default_value matches what queries accept.

The table runs on the Bindable path, where array columns can be selected and indexed but not used with Druid array functions such as ARRAY_CONTAINS. Those need the native system-table path (apache#20183).

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This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• added unit tests or modified existing tests to cover new code paths.

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[FrankChen021]

Split: system table moved upstream to apache#20586; web console change in #226.