Support unicode messages by exchange logging

[gomoripeti]

Proposed Changes

Before this commit formatting the amqp body would crash and the log message would not be published to the log exchange.

Before commit 34bcb91 it even crashed the whole exchange logging handler which caused the log exchange to be deleted.

This is the root cause (or at least one of them) why log exchange was seen deleted as described in #12100

A real world example logging unicode:

MQTT connection failed: access refused for user 'Aðª':user 'A𪛔' - invalid credentials

Kudos to @johanrhodin who found the bug with extraordinary intuition.

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• Breaking change (fix or feature that would cause an observable behavior change in existing systems)
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• Cosmetic change (whitespace, formatting, etc)
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Further Comments