Use `lodash` rather than `lodash.memoize`

[mcmire]

The changes in #246 brought in lodash.memoize so that we could memoize certain hex functions. Although it may seem that this package is a subset of lodash, it actually has not been updated in 9 years. Presumably this package was used instead of lodash to prevent an unnecessary increase to the bundle size, however, we already have lodash in the dependency tree in both Extension and Mobile, so we might as well use it (and using the whole package allows us to tree-shake unused modules much more easily anyway).