Midnight for the profile should always be at the start of the
day (midnight) for the chart.

This more closely mirrors logic in loopalyzer, as well as the intent from the
surrounding code in reportclient.js.

To illustrate the difference, I used chrome "sensors" feature to change my timezone to one that spans the dateline.

    > moment.tz('2023-01-19', 'America/Los_Angeles').endOf('day').format( )
    '2023-01-19T23:59:59-08:00'
    > moment.tz(moment('2023-01-19'), 'America/Los_Angeles').endOf('day').format( )
    '2023-01-18T23:59:59-08:00'

The old code uses a string replacement, which is equivalent to the first
test.  This causes the dates on the reports to be off by one, as well as
risks the data wrapping around the dateline so it can't be seen.  For example,
replacing "23:59:59" with "00:00:00" in the first example doesn't correctly
wrap around the dateline.

The patch introduces a way to parse the dates requested in the browser's
time zone, and then translates them to the profile's timezone.  The
difference is shown in the second example above.  With this change, the
correct date label should be rendered, and the data should start at
midnight without wrapping around the dateline.

This fixes the label on the days in the daytoday charts.  Passing a moment
object that is already zoned prevents toLocaleDateString from reinterpreting
the zone information when the date is already relative to the profile.

This also ensures that the datefilter is adjusted to the profile's zone rather
than truncating the time to the end or beginning of the day.  This should
prevent incorrectly wrapping arounnd the dateline.