Add Auth header to tei reranker provider

[Wolframko]

Validations

• [X] I believe this is a way to improve. I'll try to join the Continue Discord for questions
• [X] I'm not able to find an open issue that requests the same enhancement

Problem

Some reranking providers, such as Jina, use a text embeddings interface to provide reranking capabilities. While this is already implemented in core/context/rerankers/tei.ts, it currently lacks support for an authorization header, which prevents the use of hosting providers that require API key authentication.

Solution

Add auth header to core/context/rerankers/tei.ts. Example from official Jina doc: curl https://api.jina.ai/v1/rerank -H "Content-Type: application/json" -H "Authorization: Bearer jina_58cv_DMpG8ytA"

[RomneyDa]

This would be a great improvement to the reranker! Open to contribution for this one, some more specific integration items like this might not make it up the priority list for a while. Thanks for opening.