[PLT-2151] Vb/graphql upload plt 2151

[vbrodsky]

Description

Story: https://labelbox.atlassian.net/browse/PLT-2151

This PR refactors code from GraphQL file upload that originally was duplicated in two different classes

I have discovered that Client execute() already supports GraphQL file upload and was able to remove duplicate code from other classes

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Document change (fix typo or modifying any markdown files, code comments or anything in the examples folder only)

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Changes to Core Features

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