Add blocking unary generation

[buildbreaker]

Providing options for generating synchronous methods for unary RPC calls:

        val response = testServiceConnectClient.unaryCallBlocking(message)
        assertThat(response.code).isEqualTo(Code.UNKNOWN)
        response.failure { errorResponse ->
            assertThat(errorResponse.error).isNotNull()
            assertThat(errorResponse.code).isEqualTo(Code.UNKNOWN)
            assertThat(errorResponse.error.message).isEqualTo("test status message")
        }
        response.success {
            fail<Unit>("unexpected success")
        }

[rebello95]

Let's make sure to add docs on this to the Connect site as well

[buildbreaker]

@rebello95 Do you prefer "synchronous" or "blocking"?

[rebello95]

@rebello95 Do you prefer "synchronous" or "blocking"?

Don't have a strong preference, but leaning towards blocking. I would just avoid sync by itself

[rebello95]

What prevents this from being called multiple times?

[buildbreaker]

This isn't prevented. OkHttp also does this!