Changed "prepare data on the fly" functionality

[Marishka17]

Motivation and context

Add ability to manually prepare meta information and upload this meta information along with a video to reduce a task creation time.
Fix issue #2112

How has this been tested?

Manual tests, unit test

Checklist

• I submit my changes into the develop branch
• I have added description of my changes into CHANGELOG file
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have linked related issues (read github docs)
• I have increased versions of npm packages if it is necessary (cvat-canvas,
  cvat-core, cvat-data and cvat-ui)

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below)

# Copyright (C) 2020 Intel Corporation
#
# SPDX-License-Identifier: MIT

[Marishka17]

I need to discuss some moments with @azhavoro

[coveralls]

Coverage increased (+0.2%) to 65.106% when pulling be0ec2e on mk/fix_cache into e9552f8 on develop.

[bsekachev]

@Marishka17 @azhavoro
Is the PR ready and works? Can we merge it?

[bsekachev]

@Marishka17

Please, solve appeared merge conflicts