Added: Diode: 1.5SMC uni/bi-dir TVS diodes

Add the 1.5SMCxxA (unidirectional) and 1.5SMCxxCA (bidirectional) TVS diodes, derived from the 1.5KExxA and -CA parts.

https://www.vishay.com/docs/88303/15smc.pdf

(also Littelfuse: https://www.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_1_5smc_datasheet.pdf.pdf)

---

Other changes

• Minor changes to descriptions:
  • Move "TRANSZORB" tradename to tags - this is only a Vishay designation, but Littelfuse make this line too
  • Push "TVS" in the description and spelling it out in tags

Parts modified

• 1.5KExxA (existing - uni-dir)
  • 1.5SMCxxA (new)
• 1.5KExxCA (existing - bi-dir)
  • 1.5SMCxxCA (new)