The existing `Wacom::TabletDatabase::lookupTablet` function does not require
a companyId and so may provide an unexpected match when provided with the
tabletId of a non-Wacom tablet which has the same ID as a Wacom tablet, or
the tablet ID of a Wacom tablet which isn't in the Wacom database but matches
a non-Wacom tablet. To allow for a more reliable match, this commit adds a
version of the lookupTablet function which requires a match on both the
provided companyID and the tabletID.
The first user of this new function is testlibwacomdata.cpp which needs to