Add Embeddable integration guide for connecting to Firebolt

[hjkmarshall]

Description

Add Embeddable integration guide for connecting to Firebolt
Includes prerequisites, setup steps, API example, and links to further resources.

When should this PR be released to the public?

Immediate release.

Checklist below completed.

Documentation Checklist

• I've previewed my documentation locally running make start-local (or using this tutorial)
• I've validated that indexing works and that I'm able to navigate to the documentation page from the table of contents
• If I added SQL examples, I have validated that they run correctly and as described.

If this PR touches a function implementation (aggregate, scalar, or table-valued):

• I've made sure my documentation is aligned with these guidelines on function documentation
• I've validated that the parent of my docs page is set correctly and the function shows up in the right category of the table of contents
• I've made sure that the function was added to the function glossary