feat: implement react-feature generator

[beeman]

This PR introduces the react-feature generator that can be used to generate new features that currently consist of an Anchor program and React UI.

nx g @solana-developers/preset-react:feature -d

>  NX  Generating @solana-developers/preset-react:react-feature

✔ What name would you like to use for the feature? · second-counter
✔ Which feature would you like to generate? · anchor-counter
✔ Which UI library would you like to use? · tailwind
UPDATE anchor/Anchor.toml
CREATE anchor/programs/second-counter/Cargo.toml
CREATE anchor/programs/second-counter/Xargo.toml
CREATE anchor/programs/second-counter/src/lib.rs
CREATE anchor/src/second-counter-exports.ts
CREATE anchor/target/idl/second_counter.json
CREATE anchor/target/types/second-counter.ts
CREATE anchor/tests/second-counter.spec.ts
UPDATE anchor/src/index.ts
CREATE web/src/app/second-counter/second-counter-data-access.tsx
CREATE web/src/app/second-counter/second-counter-feature.tsx
CREATE web/src/app/second-counter/second-counter-ui.tsx

Breaking this apart makes our generators more composable and we'll likely move more things into features down the line, for example, the account and clusters screens.

The main application generators have been adopted to now use this preset so the app we generate should be the same.