[BUG] `dataset submit` only validates fields after doing a bunch more stuff

[pierre-nedelec]

Describe the bug
Only validates field after some lengthy operations, and error message doesn't say whether the command should be rerun or whether we can still change the field after the fact.

To Reproduce
Steps to reproduce the behavior:

medperf dataset submit -p 99 -d path1 -l path1 --name name --location "loc" --description "123456789012345678901"

output:

MedPerf 0.1.2
❌ Field Validation Error:
- description: ensure this value has at most 20 characters.

Expected behavior
Run such validation first so we don't have to wait 10' to see that message.

[hasan7n]

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