Show an indication of filtering on the Experiment Table webview

[rogermparent]

One issue we have in the VSCode extension is the possibility of the user looking at the experients table while unaware of any filters being applied. This is less of an issue with sorts as there's already an indicator, but filters have no feedback on the experiments table itself which becomes an issue when the user isn't currently looking at the dvc sidebar for any reason.

Ideally, we want to show both the fact that filters are applied and the amount of records that are hidden by the filter.

[mattseddon]

Couple of things that we are going to do in the short term

1. Add filtered icon to the column in the table as per screenshot:

2. Add a description to the filter by tree which states the number of rows filtered:

Both of these items are with @wolmir 👍🏻.

[shcheklein]

Add a description to the filter by tree which states the number of rows filtered:

Can we add it somewhere into the table also please? :)

[rogermparent]

Closed by #1872 and #1760