Rle mask export

[kkm-atom]

Create Brush tool by extending this branch and making changes.

Above mentioned branch has been taken for local development. latest "develop" branch is merged to keep everything up to date. Brush tool was already added in the UI but the export to COCO was incorrect. Changes have been made to export it in RLE Mask format.

There's an issue while uploading COCO. The mask does not show up. Same thing is happening in case of importing ellipse via COCO Json. This issue needs resolution

Motivation and context

Linked issues:
#4727
#4723
#1849
#2384

How has this been tested?

Checklist

• I submit my changes into the develop branch
• I have added a 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) 2022 Intel Corporation
#
# SPDX-License-Identifier: MIT

[nmanovic]

@kkm-atom , thanks for the contribution! Please give us some time to review and improve the PR. I hope to come back with more details in several weeks.

[nmanovic]

@kkm-atom , we will continue the implementation in the repository for now: #2.

[bsekachev]

Hi, @kkm-atom

Now, I will be able to finish the patch gradually in this repository and maybe to use some of your code if you do not mind.
Looking into a number of conflicts with develop branch and probably with current masks patch (which was adjusted and also has lots of conflicts with develop) it would be easier to close this pull request. Anyway, thank you for the contributing.