feature: method all for directories.

[yackers]

Summary

This PR fixes/implements the following bugs/features:

• Feature DocMan.dir.all() - get all app paths as map with one channel request #5: Added method all() for helper DocMan.dir.all() = DocManAppDirs -> all()

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Motivation

This method will allow to make only one request during initialization of an app, for example, 
when you anyway required to get all available app directories.

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How Has This Been Tested?

Example app, currently getting all directories via new method.

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Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Code style update (formatting, renaming).
• Refactoring (no functional changes, no api changes).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Documentation content changes.
• Other (please describe):

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Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

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Closing Issues

Closes #9

Screenshots

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