Release async read write for tokio v0.4.0

[GunnarMorrigan]

This change uses async reading and writing more heavily. In the past (and still for smol) data was copied to a buffer.
Parse attempts were made, these could fail and in some cases warrant a retry. For example, when not enough data is present parsing is aborted and should be retried.

This is problematic on slower connections where data comes in chunks, multiple parse attempts could be made for a single message. Due to applying async this is not the case anymore.

Writing should not see much difference

Use a buffered stream! :)

Other changes:

• Several tiny fixes
• Fuzzed the async reader to find subtle bugs (remove 2 crashing bugs)

[codecov]

Codecov Report

Attention: Patch coverage is 88.17577% with 409 lines in your changes missing coverage. Please review.

Project coverage is 88.07%. Comparing base (efe77c9) to head (634e05b).

Files with missing lines	Patch %	Lines
mqrstt/src/packets/mqtt_trait/primitive_impl.rs	67.92%	68 Missing ⚠️
mqrstt/src/packets/connack/properties.rs	80.11%	35 Missing ⚠️
mqrstt/src/packets/connect/last_will_properties.rs	56.57%	33 Missing ⚠️
mqrstt/src/packets/puback/mod.rs	51.02%	24 Missing ⚠️
mqrstt/src/packets/unsuback/properties.rs	41.17%	20 Missing ⚠️
mqrstt/src/packets/primitive/qos.rs	57.14%	18 Missing ⚠️
mqrstt/src/packets/primitive/variable_integer.rs	90.62%	18 Missing ⚠️
mqrstt/src/packets/connect/mod.rs	95.90%	17 Missing ⚠️
mqrstt/src/packets/pubcomp/mod.rs	69.23%	16 Missing ⚠️
mqrstt/src/packets/publish/mod.rs	91.12%	15 Missing ⚠️
... and 27 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #20      +/-   ##
==========================================
+ Coverage   79.70%   88.07%   +8.36%     
==========================================
  Files          32       51      +19     
  Lines        5850     5998     +148     
==========================================
+ Hits         4663     5283     +620     
+ Misses       1187      715     -472     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.