Exchange with relation targets, more batch ops

[mlange-42]

Adds methods to allow for exchanging components and setting relation targets at the same time. Includes batch operations and generic API.

• adds methods Relations.Exchange(), Relations.ExchangeBatch(), Relations.ExchangeBatchQ() for exchange with relation target
• adds Exchange.WithRelation() and optional target argument for operations with relation target
• adds MapX.AddBatch(), MapX.AddBatchQ(), MapX.RemoveBatch()and MapX.RemoveBatchQ()
• adds optional relation target argument to most MapX methods
• adds FilterX.Filter() to get an ecs.Filter from a generic one

[coveralls]

Pull Request Test Coverage Report for Build 7576871254

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 7573644274:	0.0%
Covered Lines:	6036
Relevant Lines:	6036

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💛 - Coveralls