Do not cast empty Pandas blocks to float64 when empty types are enabled

[vasil-pashov]

Describe the bug

#1561 Completely disables Pandas consolidation. In order to keep the behavior unchanged it has to cast empty blocks to float64. This should not happen with empty types. The dtype of empty column should be object.

Steps/Code to Reproduce

import pandas as pd
import arcticdb
import numpy
ac = arcticdb.Arctic("lmdb://test")
lib = ac.get_library("test_lib", create_if_missing=True)
s = pd.Series()
lib.write("test_sym", s)
assert lib.read("test_sym").data.dtype == np.object

Expected Results

>>> print(lib.read("test_sym").data.dtype == np.object)
True

OS, Python Version and ArcticDB Version

Python: 3.10.11 (tags/v3.10.11:7d4cc5a, Apr 5 2023, 00:38:17) [MSC v.1929 64 bit (AMD64)]
OS: Windows-10-10.0.22631-SP0
ArcticDB: dev

Backend storage used

No response

Additional Context

No response