Make Channel implement AutoCloseable

[adamw]

Closes #23

[github-actions]

Benchmark results

Java:
(capacity)  (chainLength)  Mode  Cnt     Score     Error  Units
BufferedBenchmark.arrayBlockingQueue             1            N/A  avgt    5  1017.007 ±  67.333  ns/op
BufferedBenchmark.arrayBlockingQueue            10            N/A  avgt    5   193.502 ±  33.597  ns/op
BufferedBenchmark.arrayBlockingQueue           100            N/A  avgt    5   116.331 ±   3.257  ns/op
BufferedBenchmark.channel                        1            N/A  avgt    5   216.174 ±  45.280  ns/op
BufferedBenchmark.channel                       10            N/A  avgt    5   185.888 ±  38.573  ns/op
BufferedBenchmark.channel                      100            N/A  avgt    5   156.230 ±  20.229  ns/op
ChainedBenchmark.channelChain                    0            100  avgt    5  1007.035 ±   4.340  ns/op
ChainedBenchmark.channelChain                    0           1000  avgt    5  1016.213 ±  17.392  ns/op
ChainedBenchmark.channelChain                    0          10000  avgt    5  1026.876 ±  16.654  ns/op
ChainedBenchmark.channelChain                  100            100  avgt    5    30.556 ±   0.654  ns/op
ChainedBenchmark.channelChain                  100           1000  avgt    5    30.479 ±   0.870  ns/op
ChainedBenchmark.channelChain                  100          10000  avgt    5    31.236 ±   1.589  ns/op
ChainedBenchmark.queueChain                      0            100  avgt    5   109.663 ±  12.628  ns/op
ChainedBenchmark.queueChain                      0           1000  avgt    5   125.174 ±  24.305  ns/op
ChainedBenchmark.queueChain                      0          10000  avgt    5   126.795 ±  38.346  ns/op
ChainedBenchmark.queueChain                    100            100  avgt    5    10.859 ±   0.638  ns/op
ChainedBenchmark.queueChain                    100           1000  avgt    5    11.017 ±   0.209  ns/op
ChainedBenchmark.queueChain                    100          10000  avgt    5     9.971 ±   0.575  ns/op
RendezvousBenchmark.channel                    N/A            N/A  avgt    5   174.572 ±  33.856  ns/op
RendezvousBenchmark.exchanger                  N/A            N/A  avgt    5    85.974 ±  15.187  ns/op
RendezvousBenchmark.synchronousQueue           N/A            N/A  avgt    5   604.921 ± 171.611  ns/op
SelectBenchmark.selectWithSingleClause         N/A            N/A  avgt    5   229.317 ±  63.647  ns/op
SelectBenchmark.selectWithTwoClauses           N/A            N/A  avgt    5   209.010 ±  17.063  ns/op

Kotlin:
(capacity)  (chainLength)  Mode  Cnt    Score     Error  Units
BufferedKotlinBenchmark.channel_defaultDispatcher                        1            N/A  avgt    5  106.512 ±   1.161  ns/op
BufferedKotlinBenchmark.channel_defaultDispatcher                       10            N/A  avgt    5   54.214 ±   0.777  ns/op
BufferedKotlinBenchmark.channel_defaultDispatcher                      100            N/A  avgt    5   32.508 ±   0.719  ns/op
ChainedKotlinBenchmark.channelChain_defaultDispatcher                    0            100  avgt    5   73.906 ±   3.939  ns/op
ChainedKotlinBenchmark.channelChain_defaultDispatcher                    0           1000  avgt    5  114.053 ± 124.448  ns/op
ChainedKotlinBenchmark.channelChain_defaultDispatcher                    0          10000  avgt    5   58.353 ±   4.273  ns/op
ChainedKotlinBenchmark.channelChain_defaultDispatcher                  100            100  avgt    5   13.970 ±   0.975  ns/op
ChainedKotlinBenchmark.channelChain_defaultDispatcher                  100           1000  avgt    5   13.848 ±   0.396  ns/op
ChainedKotlinBenchmark.channelChain_defaultDispatcher                  100          10000  avgt    5   15.135 ±   0.502  ns/op
ChainedKotlinBenchmark.channelChain_eventLoop                            0            100  avgt    5  102.354 ±   7.999  ns/op
ChainedKotlinBenchmark.channelChain_eventLoop                            0           1000  avgt    5  155.914 ±  15.449  ns/op
ChainedKotlinBenchmark.channelChain_eventLoop                            0          10000  avgt    5   94.958 ±   1.334  ns/op
ChainedKotlinBenchmark.channelChain_eventLoop                          100            100  avgt    5   29.260 ±   0.229  ns/op
ChainedKotlinBenchmark.channelChain_eventLoop                          100           1000  avgt    5   31.472 ±   0.191  ns/op
ChainedKotlinBenchmark.channelChain_eventLoop                          100          10000  avgt    5   31.386 ±   0.748  ns/op
RendezvousKotlinBenchmark.channel_defaultDispatcher                    N/A            N/A  avgt    5  148.933 ±   0.661  ns/op
SelectKotlinBenchmark.selectWithSingleClause_defaultDispatcher         N/A            N/A  avgt    5  249.941 ±  14.974  ns/op
SelectKotlinBenchmark.selectWithTwoClauses_defaultDispatcher           N/A            N/A  avgt    5  312.930 ±   1.185  ns/op