Fix frame preloading

[azhavoro]

Motivation and context

Frame preloading doesn't work due improperly initialization of FrameProvider by this commit 7512fd6#diff-44a538d6db30ba4db0034acd80cc53f908c457d6a69cecd55bc9a968c43cb26fL29

How has this been tested?

Manually

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

[coveralls]

Coverage increased (+0.001%) to 62.243% when pulling 83ada9e on az/fix_frame_preloading into 4816808 on develop.