Store entity fix (parallel upload for multiply typed items)

[MatPoppFHG]

Before:

• Solely, sequential upload is possible if items to be uploaded have diverse types, resulting in annoying save times. (for each type a parallel upload is performed, resulting essentially in sequential uploads)
  Now:
• Upload items are first collected in common list then uploaded asynchronously unless parallel=false is actively set.

[coveralls]

Pull Request Test Coverage Report for Build 11686270686

Details

• 25 of 34 (73.53%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall first build on store_entity_fix at 52.835%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/osw/core.py	23	32	71.88%

Totals
Change from base Build 11622161035:	52.8%
Covered Lines:	2589
Relevant Lines:	4599

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💛 - Coveralls

[LukasGold]

Tests ran successfully, desired behavior was achieved

[LukasGold]

@SimonStier: Why point to new_schema with schema, if not ever use schema in the code below? Is there a dict.update() call missing?

[LukasGold]

Should be treated in an additional issue / branch