N-06 [Oval] State Variable Visibility Not Explicitly Declared

[md0x]

Fixes the following issue reported in the Oval Incremental Audit:

Throughout the codebase, there are state variables that lack explicitly declared visibility:
The reporter state variable in CoinbaseOracle.sol
The SOURCE state variable in StandardCoinbaseFactory.sol
The pyth state variable in StandardPythFactory.sol

For clarity, consider always explicitly declaring the visibility of variables, even when the default
visibility matches the intended visibility.

[linear]

UMA-2653 N-06 [Oval] State Variable Visibility Not Explicitly Declared

[chrismaree]

some inconsistency here: in the src/factories/StandardCoinbaseFactory.sol the public immutable variable is all caps. here, its not. This should be standardized. same goes for the src/oracles/CoinbaseOracle.sol