[OPA] Add additional context file to Trino OPA plugin

[chiahangchang]

Add optional configuration property to Trino OPA plugin, specifying a path to a JSON containing tenant-specified context (i.e. namespace, cluster, environment, tier) as key-value pairs

Additional context and related issues

https://github.com/trinodb/trino/issues/25880

Release notes

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## Section
* Fix some things. ({issue}`issuenumber`)