Type cast in spaces families

[XuehaiPan]

1. spaces.Dict

in __init__:

• convert tuple to OrderedDict as well (same as list).
• raise AssertionError when the user does not pass a dict or list / tuple of keyvalue pairs.

---

2. spaces.Tuple:

in __init__:

• convert input spaces to tuple.

in contains:

• convert the input sample to tuple.

Fixes #2140.
Fixes #2479.

---

3. spaces.MultiBinary

in __init__:

• convert input shapes to tuple of ints.
• raise AssertionError when any entry of the input shapes is not positive.

---

4. spaces.MultiDiscrete

in __init__:

• make a copy of the input nvec.

  >>> import numpy as np
  >>> a = np.array([1, 2, 3], np.int64)
  >>> np.asarray(a) is a
  True
  
  >>> np.asarray(a)[0] = 4
  >>> a
  array([4, 2, 3])

• raise AssertionError when any entry of the input shapes is not positive (convert to ints first).

in contains:

• convert tuple to np.ndarray as well (same as list).

---

5. spaces.Discrete

in __init__:

• convert the input shape int.
• raise AssertionError when the input shape is not positive (convert to ints first).

[RedTachyon]

Overall looks good, one point around the code in this PR - do we need the OrderedDicts in spaces.Dict? Since Python 3.7 (i.e. the earliest version that's actually supported by gym), dicts are guaranteed to be ordered, so I'd probably prefer just making everything into a dict. Not sure if we need to do that in this PR though.

One other minor comment left as review

[jkterry1]

@RedTachyon are you happy with it now?

[RedTachyon]

@jkterry1 I think can be merged now, there's still a conversation to be had about dict vs OrderedDict, but that can be done in another PR

[jkterry1]

@RedTachyon can you please create an issue regarding the OrderedDict thing so it doesn't get forgotten?