Create a new `*DefaultCtx` method called `SendStreamWriter()`
that maps to fasthttp's `Response.SetBodyStreamWriter()`

- Adds Test_Ctx_SendStreamWriter to ctx_test.go

- Adds Test_Ctx_SendStreamWriter_Interrupted to ctx_test.go
    - (Work-In-Progress) This test verifies that some data is
      still sent before a client disconnects when using the method
      `c.SendStreamWriter()`.

**Note:** Running this test reports a race condition when using
the `-race` flag or running `make test`. The test uses a channel
and mutex to prevent race conditions, but still triggers a warning.