Change the default to not `npm build`

[chadoh]

trafficstars

What problem does your feature solve?

Some pro users don't want to use our TS Bindings because a whole NPM package feels too heavy.

What would you like to see?

Let's add a --file-only option to the bindings typescript command that will:

• honor the --output-dir option, and emit only [output-dir]/index.ts (NOT [output-dir]/src/index.ts)

• output a message to stdout (or stderr, whatever the rest of the file is doing) saying:

   Created [output-dir]/index.ts. NOTE: You must have an NPM project configured with:
  
    - typescript@[version from template's package.json] or compatible version
    - @stellar/stellar-sdk@[version from template's package.json] or compatible version
    - buffer@[version from template's package.json] or compatible version
  

Print that you need node and npm installed

What alternatives are there?

Don't