Store raw identifier values without SQL quoting in mz_*_source_tables catalog tables

[bobbyiliev]

Breaking change. Store raw identifier values in the mz_kafka_source_tables,
mz_mysql_source_tables, and mz_postgres_source_tables system catalog tables
without SQL quoting. For example, a Kafka topic previously stored as "my-kafka-topic"
now appears as my-kafka-topic. This change should have no user impact, but please
let us know if you run into any issues.

Fixes https://github.com/MaterializeInc/database-issues/issues/11202

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[ggevay]

LGTM

My only slight concern is that this is, strictly speaking, a breaking change. That is, in theory, somebody might be relying on us automatically quoting these, right? But you know the ecosystem of external tools that might be reading these tables better than me, so if you think the risk is minimal, then feel free to go ahead. Still, we might want to mention this in the release notes, so that if it happens to break someone's workflow, it will be at least easier for them to figure out what's going on.