WasiPreview1 takes an explicit logger to instantiate

[evacchi]

• We should allow users to instantiate WasiPreview without an explicit logger.
• As a follow-up question, possibly answered contextually to this issue, should we have a global SystemLogger public default instance? I would argue we should.

So, instead of having users to specify new SystemLogger(); the SystemLogger would:

public class SystemLogger
    private static SystemLogger DEFAULT_LOGGER = new SystemLogger();
    public static getDefaultLogger() {
        return DEFAULT_LOGGER;
    }
...

then WasiPreview1 could expose an empty constructor:

public class WasiPreview1 {
    ...
    public WasiPreview1() {
        this(SystemLogger.getDefaultLogger());
    }

}

[andreaTP]

In most places in this codebase, we locked down the instantiation of objects using builders, one option is to do the same in this context offering a consistent API experience to users.