Finishing civetconfig

[edemaine]

• VSCode extension uses default civetconfig
• CLI uses default civetconfig
• unplugin should support default civetconfig, along with config override
• eslint plugin should probably do the same
• Babel plugin should probably do the same
• Gulp plugin should probably do the same
• What about ESM and Bun plugins?
• Document in https://civet.dev/config

[danielbayley]

There are also the proposed potential config files, as @STRd6 mentioned in #647 (comment).

Allow for parsing different config file extensions based on what modules exist in the local user project

Plus I threw together a quick PR to allow civetConfig in package.json also in #1300.