Add .npmrc to workspaces

[mshima]

We use npm workspaces for scripts.
Since npm 8.5.0, npm install dedupes to the root by default.
Npm npm/cli#4437 behavior can break workspaces on transitive dependency changes at the root package.json.

So this PR tries to disable workspaces behavior by default.
Following npm/cli#4437 (comment).
Add .npmrc with workspaces=false.

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