move boilerplate for Julia and R

[gvwilson]

• Can remove the options from the package.json here: https://github.com/plotly/dash-component-boilerplate/blob/master/%7B%7Bcookiecutter.project_shortname%7D%7D/package.json#L21
• And same here: https://github.com/plotly/dash-typescript-component-template/blob/344410063c4cf1c0[…]8f9eaaf/%7B%7Bcookiecutter.project_shortname%7D%7D/package.json
• And remove the jl-prefix and r-prefix from the cookiecutters:

  dash-component-boilerplate/cookiecutter.json

  Lines 5 to 6 in 425fcc0

  	"jl_prefix": "",
  	"r_prefix": "",