Specify foraging experiments data contract using formal yaml schema

[glopesdev]

Issues have been reported where event codes have been reused inconsistently across logs (see #174). We need to ensure the data contract is enforced, but this will only become harder as experiments grow in complexity and number of components. One way to scale the approach is to formalize the data contract as a machine-readable format, which can then be used for either automatic code generation or verification of experiment-specific event codes (e.g. following Harp device schema).

[jkbhagatio]

As an exercise, we can do this for two examples and see what this looks like: can use the encoder stream and video data stream