Fixed banana generation on catch specific maps

[frankhjwx]

Fix the bug when generating bananas on catch specific maps because of lacking IHasXPosition property.

[peppy]

Your PR description says IHasEndTime but the diff is adding IHasXPosition.

[frankhjwx]

Sorry it's my fault, catch objects should have IHasXPosition property for object generating.

[peppy]

i’m not sure this is the correct fix as spinners in catch don’t actually have an x position.

[smoogipoo]

A better fix would be to re-order CatchBeatmapConverter to generate spinners if there is no position data, rather than returning early.

[frankhjwx]

@smoogipoo That's right, the main problem is caused by if (positionData == null) judgement in CatchBeatmapConvertor

Still not very familiar with git operation, failing to discard my changes on ConvertSpinner.cs.