Fix FPs around custom managed records in VariableInitialization

[Bazooper-blip]

This PR fixes false positives in VariableInitialization on custom managed records. Delphi initializes a local custom managed record automatically through its Initialize operator, but the rule tracked it like any other unmanaged record, so code like the example in the issue was flagged even though the record had been initialized.

Records that declare an Initialize operator are now treated like the managed types the rule already exempts (strings, variants, interfaces and arrays). This applies to local var sections, inline var declarations and fields of other records, where the containing record's other fields are still checked. Both the Initialize(out Dest: T) form and the implicit-Self class operator Initialize; form are recognized.

Two cases are intentionally still checked:

• Records with only a Finalize operator, since their unmanaged fields aren't initialized.
• out parameters of custom managed record types, in line with 3614f61 treating out parameters as uninitialized. This also keeps the check working inside the Initialize operator itself.

I've also listed these records as an exception in the rule description and added a changelog entry.

Fixes #468.