Closes#1851
This changes how we use the `<btrix-meter>` component: previously, we
didn't set a `max` value on it, so it was drawing its internal (rounded)
bar at 100% of the meter width, and then drawing the
`<btrix-meter-bar>`s inside that 100% width bar. This changes that, and
instead it now does the following:
- Draws the internal rounded bar to the width of the proportion of their
counts to the total page count;
- Adjusts the `<btrix-meter-bar>`s to be proportional to the completed
page count rather than the total page count
- Uses the `"available"` slot in `<btrix-meter>` to draw the remaining
"No data" bar & tooltip in the remaining space outside of the internal
rounded bar
This also includes a couple unrelated but adjacent changes:
- Changes the page count text to say "Analysis starting" when the
analysis run is starting, because there's no meaningful page count at
that point.
- Uses the pending state when the total page count is falsy (`undefined`
or `0`), rather than just `undefined`
a7382ebb98