support additional package managers

[Dominik G.]

yarn, yarn2, pnpm

requires work for svelte-hmr. needs an alias to properly resolve at dev. see vite-plugin-svelte

add -pm --packagemanager to create command

[Dominik G.]

svite-0.5.0 supports use of yarn, yarn2 and pnpm by it's changed dependency layout.

TODO:

• create command which also updates run scripts in examples
• test matrix for examples

[Dominik G.]

svite beta 0.6.0 has added tests. This will be closed once a proper release it out.