feat: add `bigframes.bigquery.create_vector_index` to assist in creating vector index on `ARRAY<FLOAT64>` columns

[tswast]

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• [ ] Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• [ ] Ensure the tests and linter pass
• [ ] Code coverage does not decrease (if any source code was changed)
• [ ] Appropriate docs were updated (if necessary)

Fixes internal issue 365541165 🦕