On click member should be selected

#### Purpose

On click on member or class it should be selected.

#### Modifications

Added `Focuse()` in `StandardPanel.OnMouseLeftButtonDown` function. Also introduced `StandardPanel.IsSearchActive` property to specify whether `StandardPanel` is shown for `LibrarySearchView` or not. For not `LibrarySearchView` we shouldn't select member on click.

#### Additional references

[MAGN-5117](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-5117).

#### Reviewers

@aosyatnik, @Benglin, please, take a look.