feat: Access stream name in __alias__

[holly-evans]

Feature scope

Taps (catalog, state, stream maps, tests, etc.)

Description

Allow users to reference the stream name in stream maps __alias__ fields, under a special key:

{
    "stream_maps": {
        "*": {
            "__alias__": "'raw_' + __stream_name__"
        },
}

{
    "stream_maps": {
        "*_pii": {
            "__alias__": "__stream_name__[:-4]",
            "email_hash": "md5(email)",
            "__else__": "__NULL__",
            "__key_properties__": ["email_hash"],
        },      
    }
}

Related

• Slack thread: https://meltano.slack.com/archives/C06A1LKFAAC/p1726223551509239
• Issue feat: Support using the stream name or alias in the context of a stream map #2283: similar but __alias__ is not currently evaluated at all so a different set of changes is needed, whereas feat: Support using the stream name or alias in the context of a stream map #2283 is adding to an existing list of keywords