[BUG] Add second speaker field in OpenSearchCon NA CfP form in Airtable

[pajuric]

Describe the bug
A second field is need or the option to add an additional speaker for people submitting the OpenSearchCon NA CfP.

To Reproduce
Steps to reproduce the behavior:

1. Go to opensearch.org
2. Click on OpenSearchCon 2024 North America
3. Scroll down to Submit a Presentation
4. Scroll down to the New CfP Submission section
5. Add the option in a drop down or using + to insert a second speaker and their information

Expected behavior
Anyone submitting the CfP who has a co-presenter will be able to include and have them listed on their CfP submission for consideration

[pajuric]

@DarshitChanpura - Request made

[nateynateynate]

I've added a second set of presenter inputs hidden behind a checkbox that the submitter can use to indicate that there will be a copresenter. I'll consider this one closed, but feel free to reopen if the new form doesn't meet your needs.