Implement proper logs subscriber

[gahag-cw]

[luiz-silveira-cw]

Problem:

tracing-stackdriver & tracing-subscriber make some Inefficient serialization to FormattedFIelds<JsonFields> -- which they call "extensions" -- to, later, deserialize, aggregate and serialize again to the final json string for the log entry.

The reasoning might be related to them supporting several formats, other than json.

To fix this, we might need:

1. Create our own tracing-subscriber, removing the flexibility around output formats and fixing it to json output only
2. Make our own tracing-stackdriver to use this new version.

Better than that:
Create a third crate with the functionality of (1) & (2), avoiding using our own versions of (1) & (2).
To consider: it may be harder to incorporate changes from upstream.

To consider: the faster minitrace -- although the refactorings to use it may be too extensive

[gahag-cw]

Alternatives:

• minitracing
• rustracing

[luiz-silveira-cw]

2 PRs are related to this:

cloudwalk/logcall#1
and
cloudwalk/infinite-errors#1

After the 1st is merged, dependencies on the 2nd must be updated.

[luiz-silveira-cw]

Additional PRs:
cloudwalk/infinite-errors#2
https://github.com/cloudwalk/infinitepay-auth/pull/369
UPDATE:
cloudwalk/logcall#2

[gahag-cw]

Deps that also use tracing:

• reqwest
• influxdb
• influxdb-dispatcher
• rocket
• bb8-redis
• redis