Change `Field.__repr__` to match representation in `pystencils.fields`
Compare changes
repr of Field should look like
y: uint16_t[246,704,558]
x(3): float[20,40]to match representation when using pystencils.fields
E.g.
In [3]: pystencils.fields('x: float32[20,40]')
Out[3]: x: float[20,40])
In [4]: pystencils.fields('x(3): float32[20,40]')
Out[4]: x(3): float[20,40])