Adds missing numpy dtypes

[ajpotts]

Adds the following missing numpy dtypes:

• integer
• intp
• number
• floating
• signedinteger

Also adds the following numpy functions:

• issubdtype
• isscalar
• iinfo
• finfo

Code examples:

In [1]: ak.connect()
   ...: import arkouda.numpy as aknp
   ...: aknp.issubdtype(ak.int64, aknp.intp)
Out[1]: True

In [2]: aknp.issubdtype(ak.int64, aknp.number)
Out[2]: True

In [3]: aknp.issubdtype(ak.int64, aknp.integer)
Out[3]: True

In [4]: aknp.issubdtype(ak.float64, aknp.floating)
Out[4]: True

In [5]: aknp.issubdtype(ak.int64, aknp.signedinteger)
Out[5]: True

In [6]: aknp.isscalar(3.5)
Out[6]: True

In [7]: aknp.isscalar("float")
Out[7]: True

In [8]: aknp.isscalar(np.arange(5))
Out[8]: False

In [9]: aknp.isscalar(ak.arange(5))
Out[9]: False

In [10]: aknp.iinfo(ak.int64)
Out[10]: iinfo(min=-9223372036854775808, max=9223372036854775807, dtype=int64)

In [11]: aknp.finfo(ak.float64).dtype
Out[11]: dtype('float64')

Closes #3289 integer dtype
Closes #3288 intp dtype
Closes #3291 number dtype
Closes #3295 floating dtype
Closes #3299 signedinteger dtype
Closes #3298 issubdtype function
Closes #3301 isscalar function
Closes #3287 iinfo function
Closes #3296 finfo funtion

[stress-tess]

looks great! thanks amanda!