feat: improve pstates UI

[makarov-roman]

addresses #894

changes:

1. hide checkboxes instead of disabling them
2. do not render list when there are no values
3. move power_state_row to dedicated file (maybe it's my habbit, but I don't really like to have multiple components in one file)
4. remove global sensitive flag, instead all inactive pstates will be dimmed via default css class.
5. move active arrow label to the left to make it more obvious where it points ( if you stretch all UI on big screen it might be hard to tell). Also it prevents list width from jumping by couple of pixels.
6. add PageSectionExpander component and wrap pstates frame into that, it's copy-paste of PageSection mostly. I've tried to implement it first on PageSection, but it was looking very hacky.
7. switch to monospace to improve consistency

[ilya-zlobintsev]

Sometimes there might not be info about an active power state (in particular, on all Intel and some AMD devices), currently it looks a bit weird in such a scenario, there should not be a gap:

Also, is it expected that the expander button is a bit out of bounds compared to the rest of the UI? (Maybe it's fine, it's just different compared to the rest of the elements)

[makarov-roman]

Also, is it expected that the expander button is a bit out of bounds compared to the rest of the UI?

I wanted to align headers themselves

[makarov-roman]

fixed

[ilya-zlobintsev]

LGTM