KAFKA-14017: Implement new KIP-618 APIs in FileStreamSourceConnector

[C0urante]

Jira

Implements the new SourceConnector::exactlyOnceSupport method in the file source connector

• When reading from stdin, returns ExactlyOnceSupport.UNSUPPORTED as we do not track offsets
• When reading from a file, returns ExactlyOnceSupport.SUPPORTED as we do track offsets and, as long as the only modifications to the file after the connector is created are appends, those offsets should be perfectly accurate

Does not implement the new SourceConnector::canDefineTransactionBoundaries method as the default is to return ConnectorTransactionBoundaries.UNSUPPORTED, which is correct for this connector as it is incapable of defining its own transaction boundaries

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[C0urante]

@showuon Would you mind giving this a pass? Should be a quick one :)

[mimaison]

LGTM, thanks @C0urante

[C0urante]

Thanks Mickael

[lucasbru]

Are you sure this change compiles? Doesn't build for me

[C0urante]

@lucasbru There's a compilation failure introduced by a change that landed on trunk between when the last commit for this PR was filed, and when it was merged. There is a fix PR already available which should be merged shortly: #12938. Apologies for the mistake!