Include `Asset.SymbolCode.pattern` as static value

[DenisCarriere]

Currently, the Regex patterns use *.pattern as value

import { Name } from "@wharfkit/antelope";

Name.pattern // => /^[a-z1-5.]{0,13}$/

Propose

One would assume that the following would exists:

import { Asset } from "@wharfkit/antelope";

Asset.SymbolCode.pattern // => /^[A-Z]{0,7}$/

I know the Regex pattern exists in Asset.SymbolCode.symbolNamePattern, but it's not intuitive at first