Write an API to allow setting stop sequence to use with Kernel Memoery

[darcome]

This is to stop the response of the LLM to a question about own documents after the right answer.

As stated by @AsakusaRinne on Discord,

"Unfortunately it's an issue in kernel memory, see https://github.com/microsoft/kernel-memory/issues/137. Don't worry, we'll wait for the response from kernel-memory at first. If they do not want to change it, we'll add an API to allow setting stop-sequence, though it may be a little inconvenient."

[github-actions]

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