feat: support AuditLog and RequestLog protos

[daniel-sanche]

If you run logger.list_logs() and encounter an unknown proto log, it will crash the library

This PR adds support for the two officially supported proto types:

• "type.googleapis.com/google.cloud.audit.AuditLog"
• "type.googleapis.com/google.appengine.logging.v1.RequestLog"

Fixes #16

[simonz130]

this is a side note for logging language syntax and not to this specific line:
I find it ugly when we concatenate strings to form a query. Perhaps, we should think about creation of an abstraction that will make forming these filters more intuitive when you read the code.
For example:

Instead of

xxx + " AND " + time_filter

it could be

x.And(new BinaryOperator(time1, operands.Equal, time2)

This could be a separate task and not part of this PR

[daniel-sanche]

That's an interesting idea. I'm not sure if that specific example would be seen as idiomatic for Python, but there's probably something interesting we could do with this

[0xSage]

2 cents: I recall in Python (and Node), this kind of interpolation is preferred

[simonz130]

please, no abbreviations in test or other method names

[daniel-sanche]

"to_api_repr" is an existing function that we can't change here without breaking the API. We could add this to the list for v3.0.0 changes (but it may not be worth the user confusion)