Fix unused variable warnings

[egarson]

src/App.tsx has a couple of unused variable warnings as indicated below.
I will submit a fix for this just now.

Compiled with warnings.

src/App.tsx
  Line 9:66:   'Config' is defined but never used       @typescript-eslint/no-unused-vars
  Line 19:6:   'Environment' is defined but never used  @typescript-eslint/no-unused-vars
  Line 35:10:  'getRpcUrl' is defined but never used    @typescript-eslint/no-unused-vars

src/components/Wallet.tsx
  Line 4:10:   'NetworkType' is defined but never used                                                                          @typescript-eslint/no-unused-vars
  Line 18:10:  '_' is assigned a value but never used                                                                           @typescript-eslint/no-unused-vars
  Line 77:6:   React Hook useEffect has a missing dependency: 'createWallet'. Either include it or remove the dependency array  react-hooks/exhaustive-deps