Use F matrix to identify labels involving latents in RAM summary

[google-labs-jules]

Updated xmu_summary_RAM_group_parameters in R/xmu.R to robustly identify latent variables by inspecting the 'F' matrix structure instead of relying on naming conventions or umxGetLatents. This ensures correct parameter typing even in complex RAM models.

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PR created automatically by Jules for task 4077347185820115658 started by @tbates

[google-labs-jules]

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