Creates a tag for a defined tag constant in a given IFD if that IFD is allowed for the ExifTagKey. This method will fail anytime the appropriate for this tag's datatype would fail.
Return
an ExifTag object or null if one could not be constructed.
See also
#buildTag
Parameters
ifdId
the IFD that the tag should be in.
tagId
a tag constant, e.g. {@see #ExifTagKey.IMAGE_WIDTH} .