Add support for imagemin-jpegtran

[Frank3K]

Is your feature request related to a problem? Please describe.
Currently JPEG images can only be optimized using imagemin-mozjpeg. This compression is lossy and can (possibly) degrade the quality of an already lossy file.

Describe the solution you'd like
imagemin-jpegtran could be used to losslessly optimize JPEG images.

Describe alternatives you've considered
An alternative is to optimize the images using jpegtran offline, but that beats the purpose of this module. Example:

jpegtran -optimize -progressive -copy none -outfile <file.jpg> <file.jpg>

Additional context
None. 👍 for creating this module.