Improve logging for ETags and FUSE operation flags

[dannycjones]

Description of change

Small logging improvements I wanted to make while debugging #614.

• It was useful to include the ETag at different points, but the named-field struct for ETag meant the Debug format was noisy. Moving to a tuple struct is simple and ETag is now formatted as ETag("etag").
• FUSE operations which take flags were originally formatting the flags as decimal numbers. It's appears easier to interpret the flags when using binary usually, so we update the logs to format those numbers as binary like 0b10010101.
• Some of the logs on their own weren't useful. For example, we know an Inode lookup count was incremented but we only know the parent Inode. Fix that by including the Inode number that actually had its count incremented.
• We never emitted the new file handle number before use - now we do that.

Relevant issues: N/A

Does this change impact existing behavior?

No breaking changes.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and I agree to the terms of the Developer Certificate of Origin (DCO).

[passaro]

LGTM