[Storage] Implement png specific splits.

[fboucquez]

The split could be done 1) when storing the chunks (so each chunk is a specific png section) or 2) when loading the chunks (only a subsection of the 1024 chunk is processed and returned from the message)

1. On the way in: https://github.com/symbol/garush/blob/main/packages/storage/src/FileParser.ts#L16 Find a nice lib to split. Chunks could be smaller, so more aggregates are required. The network fees would be slightly higher.

2. On the way out: It depends on how "file" headers are loaded [Storage] Implement File "Header" loading #5

Note that atm rest and the SDK don't let you load just 1 transfer inner transaction of an aggregate transaction. The whole initial 100 transfers of the first data aggregate would be loaded.