Synchronous API with batching support

[sjwang90]

Proposal:
synchronous API with batching support

Current behavior:
async API is wrong-headed for Go

Desired behavior:

WriteAPIBlocking.WriteRecord could add stuff to a batch, and when the batch needs sending, it could send it. Adding a Flush method that may return an error from a previous write is sufficient, there doesn’t need to be any goroutines / channels at all. See e.g. https://pkg.go.dev/bufio#Writer.Flush

Alternatives considered:
Describe other solutions or features you considered.

Use case:
Why is this important (helps with prioritizing requests)?

@lesam