Better handling of SIGINT

[jasnell]

Currently if I run workerd server config.capnp and ctrl-c to exit, the output to the console is a very unfriendly...

bazel-bin/src/workerd/server/workerd serve /home/james/cloudflare/woerd/samples/helloworld/config.capnp 
^C*** Received signal #2: Interrupt
stack: /lib/x86_64-linux-gnu/libc.so.6@11f46d bazel-bin/src/workerd/server/workerd@7347d23 bazel-bin/src/workerd/server/workerd@72849c0 bazel-bin/src/workerd/server/workerd@7285748 bazel-bin/src/workerd/server/workerd@23cb7ce bazel-bin/src/workerd/server/workerd@23ca7d9 bazel-bin/src/workerd/server/workerd@23ca368 bazel-bin/src/workerd/server/workerd@23ca33e bazel-bin/src/workerd/server/workerd@23ca273 bazel-bin/src/workerd/server/workerd@23ca243 bazel-bin/src/workerd/server/workerd@73af5ef bazel-bin/src/workerd/server/workerd@73abe1d bazel-bin/src/workerd/server/workerd@73b5f50 bazel-bin/src/workerd/server/workerd@73afcd1 bazel-bin/src/workerd/server/workerd@73aabe1 bazel-bin/src/workerd/server/workerd@73b5f50 bazel-bin/src/workerd/server/workerd@73afcd1 bazel-bin/src/workerd/server/workerd@73ad4eb bazel-bin/src/workerd/server/workerd@73ad488 bazel-bin/src/workerd/server/workerd@7363cef bazel-bin/src/workerd/server/workerd@73a7ecc bazel-bin/src/workerd/server/workerd@73a7cbd bazel-bin/src/workerd/server/workerd@23a32dd /lib/x86_64-linux-gnu/libc.so.6@24082 bazel-bin/src/workerd/server/workerd@23a302d
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In this case, it would be ideal if there wasn't a gnarly stack printed (or any stack)... Perhaps if the --verbose option is enabled, printing the stack would be fine?