Allow passing inline config value to cli

[aszenz]

It's great that you can specify a file path for malloy config but in many cases it's easier to specify it inline with a cmd option.

Primary use case is for scripts that fetch secrets and want to pass it to malloy-cli for compilation.

Three options exist for passing inline config to malloy-cli:

1. As argument -c "{"is": "mysql", ...}"
2. As env variable MALLOY_CONFIG="{}"
3. As std input -c "-", then pass it via stdin

[aszenz]

@mtoy-googly-moogly Wdyt about this one, I also created another issue #148

[aszenz]

It would be nice to also support json output for error reporting and run timing, so that the cli can be called programmatically. Maybe similar to #146