Help as a support

I don't think there's a mastery for it, but the item relic shield does it. Also take bandit as a mastery to help you

It's an item Targon's Shield or Braces or something. The one with health and blue charges surrounding you, right?

There is no mastery for that.

Why would you want to give gold to your adc? just get gold for yourself and carry him.

That would be the passive from Relic Shield & it's upgrades, which only works with melee basic attacks

Its the ADC's job to last hit minions, there is a item for supports that helps if you accidently take some CS, but otherwise you should be poking the other adc/sup and warding everything so you don't get ganked and try to set the other ADC back. A support's main job in my opinion is to help the ADC get ahead of the game, since most adc's need help early game so they can carry late game. try to not even touch minions, a decent ADC will have them covered so you can harass the enemy ADC.

cringes at people saying support shouldnt worry about minions

That aside, Relic Shield, Targon's Brace, Face of the Mountain and its Eye equivilant have "spoils of war" which is what you are looking for.

And because I just cant stand letting the remarks slide......

Spoils of War activates with ranged or melee champions. The EXECUTE does not work for ranged champions. It still heals and gives gold to the adc.

A support's job is not to only poke, ward, and attempt to set the enemy back. Could be how some supports are meant to be played but if you go the route with Spoils of War, you are granted an additional job. Proc that Spoils to heal the adc if you are a tank with no heals of your own. Get cs for the adc that they might have missed. I mean yeah its not the end of the world if the adc takes every minion and does not let you proc it, but the amount of times it has healed just enough to keep my ADC alive and pull out a kill, 2, or more..... lets just say ADCs have learned to let the support proc that Spoils of War.