Support seedings with mixed data types

[Drarig29]

Currently, the type of an input seeding is (number | string | null)[] but we could consider this:

(number | null)[] | (string | null)[]

Because we have this logic:

brackets-manager.js/src/create.ts

Lines 487 to 490 in fc19bff

	if (helpers.isSeedingWithIds(this.stage.seeding))
	return this.getSlotsUsingIds(this.stage.seeding, positions);
	return this.getSlotsUsingNames(this.stage.seeding, positions);

Supporting this would allow to give [1, 'Team 2'], which would use the existing participant with ID 1 and create a "Team 2" participant.