Redesign concept of mapping to labels

[mishamyte]

Now concept of filters is unusable in 3/4 cases

And as it is told in https://github.com/serilog-contrib/serilog-sinks-grafana-loki/issues/81#issuecomment-1026919565:

2. Can you imagine any case when filtrationMode = null will be a desired behaviour? I doubt it and right now this is a default value. Because filtration implies some performance impact I would make this entire feature to be optional. Would be great to say "I do not need automatic labeling at all."

[mishamyte]

Concept implemented in early versions of v8:

• Filtering removed
• Labels behavior is unchanged: global label always translated as label (cause it is defined explicitly)
• Now user defines the list of prop's names which will be translated to labels. The would not appear in message body to avoid duplication (the same as now)
• Global label has more priority that mapped from property:

I.E. global label: Some: 42 Log.Information("{Some}", "word")

Result: Some: 42