Added ADR1399KHZ/KEZ

Added ADR1399KHZ/KEZ Oven-Compensated, Buried Zener, 7.05 V Voltage Reference

Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/adr1399.pdf

Footprint MR (KEZ variant): kicad-footprints!3246 (closed)
KHZ variants uses the same footprint Analog_TO-46-4_ThermalShield as LM399.

Screenshots:

• Remove the instructional content of this template
• Provide a URL to a datasheet for the symbol(s) you are contributing
• An example screenshot image is very helpful
• Ensure that the associated footprints match the official footprint library
  • A new fitting footprint must be submitted if the library does not yet contain one.
• If there are matching footprint PRs, provide link(s) as appropriate
• Check the output of the automated check scripts - fix any errors as required
• Give a reason behind any intentional library convention rule violation.
  • Violating S3.1 - https://klc.kicad.org/symbol/s3/s3.1/ KEZ Symbol is offset 50mil to align pins with 100mil grid
  • Violating S5.1 - https://klc.kicad.org/symbol/s5/s5.1/ Missing footprint MR: kicad-footprints!3246 (closed)