WiP: chore(xo-server/redis): serialize with JSON

[julien-f]

Serialize all data with JSON at the collection level.

• simplify code
• supports all types without needing special handling

To merge just after a release to have a full cycle to test!

Check list

Check items when done or if not relevant

• PR reference the relevant issue (e.g. Fixes #007)
• if UI changes, a screenshot has been added to the PR
• CHANGELOG:
  • enhancement/bug fix entry added
  • list of packages to release updated (${name} v${new version})
• documentation updated

Process

1. create a PR as soon as possible
2. mark it as WiP: (Work in Progress) if not ready to be merged
3. when you want a review, add a reviewer
4. if necessary, update your PR, and re- add a reviewer

[julien-f]

This should be tested thoroughly before being merged.

[pdonias]

There seems to be an issue here:

xen-orchestra/packages/xo-server/src/models/plugin-metadata.js

Lines 43 to 52 in c839040

	try {
	pluginMetadata.configuration =
	configuration && JSON.parse(configuration)
	} catch (error) {
	console.warn(
	'cannot parse pluginMetadata.configuration:',
	configuration
	)
	pluginMetadata.configuration = []
	}