Multi-descriptions for a Dataset/Project

[NShaforostov]

Background
At the moment, due to #438 user can attach html page to a dataset, and that page will be displayed at the "Browser" panel as the description page of the opened dataset.
Currently, any dataset can have only one description page. But it would be convenient to have the ability to add any count of descriptions.

Approach

At the CLI:

Expand the functionality of the existing CLI command add_description:

1. Add the option -n (--name). This option should allow to specify the alias name for the adding description file
2. Allow to add any count of description file for a dataset

Expand the functionality of the existing CLI command remove_description:

1. Add the ability to specify a certain description file to remove from descriptions of the dataset. User shall have the ability to specify a description for removing by its alias or file name, e.g. remove_description <my_dataset> <description_name>
2. Command without specifying a certain description shall delete all descriptions from a dataset

At the GUI:

1. Full list of the dataset descriptions shall be displayed in the same dropdown in the "Browser" panel header, that currently is used to select a dataset view between description-view, summary or markdown-notes:
   • name of the description in the list should be displayed as: <description_name> (if alias name was set) or <description_file_name> (if alias name wasn't set)
   • list of the descriptions should be sorted by their names
   • item "Summary" should be moved to the top of the dropdown list
     
   • user shall click the description from the list to open it. There shall not be the ability to open several descriptions simultaneously
2. If a dataset has several descriptions - when user opens it, the first description from the list (first alphabetically) should be opened in the "Browser" panel.
3. If a dataset has no descriptions - when user opens it, the "Summary" view shall be opened in the "Browser" panel.

[Tatyana2022]

Bug was found:
The description is blinking with each new open file belonging to the same dataset

Steps to reproduce:

1. Go to NGB
2. Go to DATASETS panel
3. Select files one by one in SV_Sample1 dataset
4. Look at BROWSER panel

Expected result:
Description should be open in the panel browser without blinking

Actual result:
The description is loaded anew every time and blinking with each new open file belonging to the same dataset
3 requests are sent in the network

2021-10-20.13.48.41.mov

@rodichenko @mzueva

[Tatyana2022]

Bug was found:
The view switches from Description to Summary when unselected at least one file from several datasets with one reference

Steps to reproduce:

1. Go to NGB
2. Go to DATASETS panel
3. Select any file in SV_Sample1 dataset
4. Select SV_Sample2 dataset
5. Go to BROWSER header
6. Expand view menu
7. Select any description (e.g. desc.html)
8. Go to SV_Sample2 dataset
9. Unselect any file
10. Look at BROWSER panel

Expected result:
The description view should be displayed in the browser panel (desc.html)

Actual result:
Summary view displays in the browser panel

2021-10-20.14.11.28.mov

@mzueva @NShaforostov Could you please confirm which is correct: the bug or the current behavior?