Add option to get human readable timestamps back from `get_tabular_change_log`

[bdpedigo]

I often do something like this

import datetime

import pytz
from caveclient import CAVEclient

root_id = 864691135851320007

client = CAVEclient("minnie65_phase3_v1")

log = client.chunkedgraph.get_tabular_change_log(root_id)[root_id]
log["timestamp"] = log["timestamp"].apply(
    lambda x: datetime.datetime.fromtimestamp(x / 1000, pytz.UTC)
)

but it's hard to remember the magic words to convert timestamps, that 1000 factor is odd, etc.

What do people think about something like

client.chunkedgraph.get_tabular_change_log(root_id, convert_timestamps=True)

to automatically do a conversion like that on the return?