Convert main.parameters.json to main.bicepparam

[jongio]

This https://github.com/Azure-Samples/azure-search-openai-demo/blob/main/infra/main.parameters.json

Can be converted to biccepparam file.

[brunoborges]

What's the benefit?

[jongio]

It is the new recommend approach and less verbose.

[brunoborges]

@dantelmomsft another one for review, please

[brunoborges]

@jongio can you share a PR?