Add new Gladia integration with a GladiaTranscriber component

Summary and motivation

Currently Haystack has a RemoteWhisperTranscriber, LocalWhisperTranscriber and an integration with Elevenlabs.
This issue is about adding a new integration with Gladia for real-time audio transcription: https://www.gladia.io/product/real-time

Detailed design

A new GladiaTranscriber component (or a GladiaSpeechToText component) implemented in a similar way as the existing RemoteWhisperTranscriber component.

Checklist

If the request is accepted, ensure the following checklist is complete before closing this issue.

Tasks

• The code is documented with docstrings and was merged in the main branch
• Docs are published at https://docs.haystack.deepset.ai/
• There is a Github workflow running the tests for the integration nightly and at every PR
• A new label named like integration:<your integration name> has been added to the list of labels for this repository
• The labeler.yml file has been updated
• The package has been released on PyPI
• An integration tile with a usage example has been added to https://github.com/deepset-ai/haystack-integrations
• The integration has been listed in the Inventory section of this repo README
• The feature was announced through social media

If you want to contribute with a PR, make sure to have a Gladia API key yourself to test your implementation.