test: enhance test framework to support primitive keys

[big-andy-coates]

Description

Enhanced the test framework to work with test cases with BIGINT and DOUBLE keys. This was previously failing due to Jackson deserializing the JSON describing the expected values into to INT and DECIMAL.

To achieve this I've started to tidy up the mess in the test framework. Specifically, we no longer track the serde to use in the Topic class, as this is constructed when parsing the test cases. Doing so was problematic as it was hard to know what serde should be used just from the test case text. The serde to use is now determined by looking at the format of sources in the metastore once the SQL statements have been executed.

Also includes some additional test cases for pull queries working with primitive keys, and pulling out the code that determines the format / serde to use for a topic into a TopicInfoCache, as this is not shared by QTT and RQTT tests.

Testing done

mvn integration-test

Reviewer checklist

• Ensure docs are updated if necessary. (eg. if a user visible feature is being added or changed).
• Ensure relevant issues are linked (description should include text like "Fixes #")

[big-andy-coates]

test this please

[big-andy-coates]

retest this please

[big-andy-coates]

Merging without review as its test only change...