Improve saas + rest-api starter

[jondot]

• Organize route generation: Organize which routes are prefixed with "/api" #818
• Create default initializer hook, with the standard view engine Create default initializers #509
  • make sure lightweight template has no initializers (override with empty)
• Remove notes.rs, move user.rs profile into /auth/current (which makes user.rs removable and remove it.). after this, controllers/ folder has only mod.rs and auth.rs see also Clean Starter #820
• Add to starter generation option "API" along with "client side" and "server side" asset serving. API option will set up NO asset serving

After these steps saas and rest-api starters will be similar, and we can remove one of them, call the new starter app.

Final prep checklist

• update "old" starters -> into template in loco new
• transform current CI starters into a series of commands loco new
• update docs: use cargo install loco instead of cargo install loco-cli
• make starter description in prompt menu identical to old loco-cli
• final grep of loco-cli and replacement with loco
  • convert loco-gen tests from loco-cli to loco-new (in model.rs) and update CI to install loco-new
• loco-cli mark as deprecated
• check if we need cargo uninstall loco-cli as instruction (loco binary used by both)
• release loco CLI
  version policy:
  cli: 0.x.y -> x sync'd with framework, y runs independently
  framework: 0.x.y -> x sync'd with cli, y runs independently
• cargo framework version in Cargo.toml should say 0.x and not specify patch version