feat(whispering): add training opt-out setting for Deepgram

[wmjchen]

Summary

This PR allows Whispering users using the Deepgram API to opt out of the Deepgram Model Improvement Partnership Program by adding the mip_opt_out=true parameter to their API requests. Users who opt-out using this switch will not have their transcriptions included within Deepgram's training dataset, but may incur an additional 50% cost for opting out.

Changes:

• transcription.ts now includes a mipOptOut parameter for the Deepgram provider
• add a mipOptOut option to deepgram.ts
• add a default setting of false for mipOptOut in settings.ts
• add a LabeledSwitch to +page.svelte that allows a user to toggle mipOptOut, with a warning that it may increase costs.

I tested this by sending transcriptions to Deepgram, and reviewing my usage in Deepgram's console (Usage -> Logs), with the LabeledSwitch toggled to false and true respectively.

Thank you as always for making this software freely available.