feat: ramdisk option, webpack-plugin-ramdisk implementation

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This PR contains:

• bugfix
• feature
• refactor
• tests
• documentation
• metadata

Breaking Changes?

• yes
• no

Please Describe Your Changes

This feature adds a new ramdisk option to the configuration, which can enable the use of webpack-plugin-ramdisk to improve build emit performance (especially useful during hmr/liveReload use).

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@ndelangen please review

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@cpylua @TrySound just pushed a bunch more changes based on feedback, and some error conditions that might come up. please have another look.

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• Is it possible to reduce the amount of istanbul ignores?
• Are the snapshots system independent? I see some path errors that might need some normalization to work across multiple developers. i.e. /Users/powella/....

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Is it possible to reduce the amount of istanbul ignores?

Not necessary. The blocks that are ignored don't need to be analyzed for coverage.

Are the snapshots system independent? I see some path errors that might need some normalization to work across multiple developers. i.e. /Users/powella/....

That's really weird that CI passed with those in there.

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Since there doesn't appear to be any functional objection, I'm probably going to release this later today one I fix up that test snapshot.