Support custom Block Types

[rh-km]

The prefect API and CLI support registering of custom block types:
https://docs.prefect.io/v3/develop/blocks#create-a-new-block-type
https://app.prefect.cloud/api/docs#tag/Block-schemas/operation/create_block_schema_api_accounts__account_id__workspaces__workspace_id__block_schemas__post

It would be great if this could be exposed through the provider, so we could create and reference custom block types along with our other prefect resources in terraform.

[mitchnielsen]

This might be doable - we're picturing a resource called prefect_block_schema with the relevant fields, and then being able to use the output from that resource in the prefect_block definition.

I don't have a timeline available right now, but we'll aim to get to this fairly soon. Also welcoming pull requests 👍🏼

[serinamarie]

Sounds good, thank you @mitchnielsen !