fix(init): use temp node_modules folders for deno init --npm ...

[dsherret]

Changes it to use a temp directory for node_modules folders for deno init --npm

Closes #29513

[bartlomieju]

I'm not sure I'm a fan of this PR - I think it's better to have "node_modules" directory, than some packages not work. Can you give some more context on why you think this is better?

[dsherret]

@bartlomieju it currently creates a node_modules folder in the cwd, which then needs to be deleted (or gets merged into the current project if initializing in the cwd):

> deno init --npm <some-package>
...follow prompts and create an "example" project...
> ls
node_modules
example

[dsherret]

[nathanwhit]

We should put them in a temp directory. That's what other package managers do

[nathanwhit]

nice, LGTM!