feat: standalone binary (pnpm#92)

* feat: add an option to install the self-contained binary version of pnpm

* test: add a test about nodejs_bundled

* style: remove an empty line

* chore: use newer pnpm

* chore: update dependencies

* feat: rename `nodejs_bundled` to `standalone`

as @zkochan suggested

* docs: add

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Co-authored-by: Takashi Sato <takashi@tks.st>

Merge pull request pnpm#75 from ojeytonwilliams/fix/caching-example

docs: update the caching example

Merge pull request pnpm#56 from i7eo/master

chore: bump node version