Separate Sink, Source & CloseableChannel interfaces

[adamw]

Closes #11

[github-actions[bot]]

Benchmark results

``` Java: (capacity) (chainLength) Mode Cnt Score Error Units BufferedBenchmark.arrayBlockingQueue 1 N/A avgt 5 1035.919 ± 74.658 ns/op BufferedBenchmark.arrayBlockingQueue 10 N/A avgt 5 179.955 ± 48.918 ns/op BufferedBenchmark.arrayBlockingQueue 100 N/A avgt 5 114.026 ± 3.927 ns/op BufferedBenchmark.channel 1 N/A avgt 5 201.463 ± 57.116 ns/op BufferedBenchmark.channel 10 N/A avgt 5 185.132 ± 40.618 ns/op BufferedBenchmark.channel 100 N/A avgt 5 156.564 ± 32.471 ns/op ChainedBenchmark.channelChain 0 100 avgt 5 1015.517 ± 7.093 ns/op ChainedBenchmark.channelChain 0 1000 avgt 5 1017.394 ± 25.045 ns/op ChainedBenchmark.channelChain 0 10000 avgt 5 1024.424 ± 22.666 ns/op ChainedBenchmark.channelChain 100 100 avgt 5 30.934 ± 0.504 ns/op ChainedBenchmark.channelChain 100 1000 avgt 5 30.089 ± 1.029 ns/op ChainedBenchmark.channelChain 100 10000 avgt 5 32.276 ± 2.031 ns/op ChainedBenchmark.queueChain 0 100 avgt 5 130.703 ± 24.590 ns/op ChainedBenchmark.queueChain 0 1000 avgt 5 134.679 ± 22.130 ns/op ChainedBenchmark.queueChain 0 10000 avgt 5 131.210 ± 6.941 ns/op ChainedBenchmark.queueChain 100 100 avgt 5 11.152 ± 0.316 ns/op ChainedBenchmark.queueChain 100 1000 avgt 5 10.923 ± 0.547 ns/op ChainedBenchmark.queueChain 100 10000 avgt 5 9.365 ± 0.344 ns/op RendezvousBenchmark.channel N/A N/A avgt 5 178.396 ± 39.509 ns/op RendezvousBenchmark.exchanger N/A N/A avgt 5 94.380 ± 10.225 ns/op RendezvousBenchmark.synchronousQueue N/A N/A avgt 5 616.833 ± 17.666 ns/op SelectBenchmark.selectWithSingleClause N/A N/A avgt 5 225.474 ± 26.958 ns/op SelectBenchmark.selectWithTwoClauses N/A N/A avgt 5 213.507 ± 14.808 ns/op Kotlin: (capacity) (chainLength) Mode Cnt Score Error Units BufferedKotlinBenchmark.channel_defaultDispatcher 1 N/A avgt 5 120.901 ± 0.753 ns/op BufferedKotlinBenchmark.channel_defaultDispatcher 10 N/A avgt 5 54.168 ± 0.653 ns/op BufferedKotlinBenchmark.channel_defaultDispatcher 100 N/A avgt 5 31.581 ± 4.569 ns/op ChainedKotlinBenchmark.channelChain_defaultDispatcher 0 100 avgt 5 70.248 ± 3.209 ns/op ChainedKotlinBenchmark.channelChain_defaultDispatcher 0 1000 avgt 5 64.599 ± 3.027 ns/op ChainedKotlinBenchmark.channelChain_defaultDispatcher 0 10000 avgt 5 60.507 ± 2.063 ns/op ChainedKotlinBenchmark.channelChain_defaultDispatcher 100 100 avgt 5 13.745 ± 0.399 ns/op ChainedKotlinBenchmark.channelChain_defaultDispatcher 100 1000 avgt 5 13.106 ± 0.437 ns/op ChainedKotlinBenchmark.channelChain_defaultDispatcher 100 10000 avgt 5 15.156 ± 0.951 ns/op ChainedKotlinBenchmark.channelChain_eventLoop 0 100 avgt 5 102.830 ± 8.335 ns/op ChainedKotlinBenchmark.channelChain_eventLoop 0 1000 avgt 5 142.288 ± 17.504 ns/op ChainedKotlinBenchmark.channelChain_eventLoop 0 10000 avgt 5 95.203 ± 4.529 ns/op ChainedKotlinBenchmark.channelChain_eventLoop 100 100 avgt 5 29.820 ± 1.205 ns/op ChainedKotlinBenchmark.channelChain_eventLoop 100 1000 avgt 5 28.879 ± 0.387 ns/op ChainedKotlinBenchmark.channelChain_eventLoop 100 10000 avgt 5 30.777 ± 0.449 ns/op RendezvousKotlinBenchmark.channel_defaultDispatcher N/A N/A avgt 5 142.669 ± 3.832 ns/op SelectKotlinBenchmark.selectWithSingleClause_defaultDispatcher N/A N/A avgt 5 256.774 ± 0.811 ns/op SelectKotlinBenchmark.selectWithTwoClauses_defaultDispatcher N/A N/A avgt 5 323.104 ± 1.998 ns/op ```