Add CUPS printing system bindings to c.s.j.p.unix

[dbwiddis]

Adds Cups interface to c.s.j.p.unix providing JNA bindings for libcups, the Common UNIX Printing System library available on Linux, macOS, and other UNIX platforms.

Structures

Structure	C type	Description
CupsDest	cups_dest_t	Printer/class destination with name, instance, and options
CupsOption	cups_option_t	Name/value option pair
CupsJob	cups_job_t	Print job with ID, state, title, user, and timestamps

Functions

Function	Description
cupsGetDests / cupsGetDests2	Enumerate available printers
cupsFreeDests	Free destination list
cupsGetDest	Find a printer in a list by name
cupsGetNamedDest	Optimized single-printer lookup
cupsGetDefault	Get default printer name
cupsGetOption	Read an option value
cupsAddOption	Add/replace an option
cupsFreeOptions	Free options array
cupsGetJobs2	Get print jobs (active/completed/all)
cupsFreeJobs	Free job array
cupsCancelJob	Cancel a print job
cupsServer / cupsSetServer	Get/set CUPS server
cupsUser / cupsSetUser	Get/set CUPS user
cupsLastError / cupsLastErrorString	Error reporting

Constants

• Printer state: IPP_PRINTER_IDLE, IPP_PRINTER_PROCESSING, IPP_PRINTER_STOPPED
• Printer type flags: CUPS_PRINTER_CLASS, CUPS_PRINTER_COLOR, CUPS_PRINTER_DUPLEX, etc.
• Job state: IPP_JSTATE_PENDING through IPP_JSTATE_COMPLETED
• Job filters: CUPS_WHICHJOBS_ALL, CUPS_WHICHJOBS_ACTIVE, CUPS_WHICHJOBS_COMPLETED

Closes #1710

Test Output

On my local mac with actual printers:

[junit] Testsuite: com.sun.jna.platform.CupsTest
[junit] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.393 sec
[junit] 
[junit] ------------- Standard Output ---------------
[junit] Default named dest: HP_ENVY_6000_series
[junit] Number of CUPS destinations: 2
[junit] First destination: SecurePrintAMER
[junit]   printer-info: Secure Print AMER
[junit]   printer-state: 3
[junit]   printer-type: 2109692
[junit] CUPS server: /private/var/run/cupsd
[junit] Number of CUPS jobs: 50
[junit] First job: id=4 dest=HP_ENVY_6000_series title=Microsoft Word - Guidelines.docx state=9
[junit] CUPS user: dbwiddis
[junit] Default printer: HP_ENVY_6000_series
[junit] ------------- ---------------- ---------------