Restrict Run.hash to auto-generated values only

[alberttorosyan]

Proposed refactoring or deprecation

Do not allow specifying arbitrary string as a Run.hash. Currently Run.hash values can be any string including characters which are not alphanumeric. This brings some issues with hash value parsing (check this issue for the reference #1810)

Motivation

Fix all the issues related to special characters in Run.hash. Avoid accidental Run creation due to typos.

Pitch

Fix Run.hash to the auto-generated hashes only. Raise an error if specified hash is not found in Repo