Create SOL price provider and integrate it with airdropper

[ivandzen]

Implement PriceProvider component to airdropper service.
PriceProvider must periodically fetch SOL price from pyth.network oracle contract and calculate airdrop amount in NEONs. Airdrop amount must be equal to half of account creation price (0.00472692 SOL) considering NEON price is $0.25