parse tap transformers from psse

[m-bossart]

Parse all transformers from PSSE as tap transformer by default, to avoid parsing mixed transformer types in parallel.

[Copilot]

Pull request overview

This PR adjusts PSSE branch-type inference so that PSSE transformers are parsed as TapTransformer by default (rather than sometimes Transformer2W), aiming to avoid mixed transformer-type parsing (e.g., in parallel workflows).

Changes:

• Updated PSSE branch-type inference to return TapTransformer for (non-phase-shifting) transformers regardless of tap controllability.
• Updated PSSE parsing tests to look up the affected transformers as TapTransformer instead of Transformer2W.
• Updated a related warning message in _determine_control_modes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/parsers/power_models_data.jl	Changes PSSE transformer type selection to prefer TapTransformer; adjusts related warning message.
test/test_parse_psse.jl	Updates PSSE parsing tests to expect TapTransformer for specific transformers previously retrieved as Transformer2W.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

[m-bossart]

The downstream cross package test failures in PSI are due to network formulations that require all device types to be formulated.