add express example, framework selector and use existing package.json (just update it)

packages/create-llama/create-app.ts

packages/create-llama/index.ts

packages/create-llama/templates/index.ts

.../create-llama/templates/simple/express/README-template.md

packages/create-llama/templates/simple/express/eslintrc.json

packages/create-llama/templates/simple/express/index.ts

packages/create-llama/templates/simple/express/package.json

...emplates/simple/express/src/controllers/llm.controller.ts

...te-llama/templates/simple/express/src/routes/llm.route.ts

packages/create-llama/templates/simple/express/tsconfig.json

packages/create-llama/templates/simple/nextjs/package.json

packages/create-llama/templates/types.ts