Add memory leak test

[jean-roland]

Closes #657.

Also fixes 2 memory leaks that were detected by the test.

Currently the test covers the following test-cases:

• A failed session open
• Basic pub/sub
• pub/sub with attachement
• Basic query/queryable
• query/queryable with attachment and value

It can be extended in the future

[github-actions[bot]]

PR missing one of the required labels: {'bug', 'new feature', 'documentation', 'internal', 'breaking-change', 'dependencies', 'enhancement'}