Fully Integrate Minecraft Dict Environments

[decodyng]

This PR works to make Minecraft environments more generally compatible with the ILR training framework, including those environments that have Dict Action/Environment spaces

NOTE: This is a draft PR until the branches torch_conversion and then ilr_wrappers get merged into realistic_benchmarks, since the functionality here depends on implements new to those branches.

Modifications in this branch:

• Modify Minecraft data-loading and env-loading code so that you can pass in an arbitrary set of wrappers in an env_cfg config entry, and have those wrap both the observations/actions coming from the loaded dataset, and also the actual live environment (Previously, there was single hardcoded wrapper applied to all Minecraft envs)
• Add config options for using a SpaceFlattenedActorCriticPolicy (implemented in realistic_benchmarks) for environments that require it (i.e. environments with Dict-like Action spaces)
• Modify our test configs list such that we only add Minecraft to the list of test configs when it is available as a benchmark (required because the actual config entry itself now requires an import from realistic_benchmarks, which relies on minerl being installed)