Add experiment flags for modules to opt in to

[NathanFlurry]

Motivation

Need to be able to test a lot of features without stabilizing them.

Implementation

Allow the module to specify experiments to opt in to in the module.json.

Alternatives

Define this at the project config instead. But this means we can't dogfood experimental features internally before shipping. The concern is more about preventing breaking changes, so it's OK if modules use experimental features.

[linear]

OGBE-173 Add experiment flags for modules to opt in to