Implement Index/MultiIndex.equals

[HyukjinKwon]

import databricks.koalas as ks
idx = ks.Index(['a', 'b', 'c'])
midx = ks.MultiIndex.from_tuples([('a', 'x'), ('b', 'y'), ('c', 'z')])
idx.equals(idx)
midx.equals(idx)
from databricks.koalas.config import option_context
with option_context('compute.ops_on_diff_frames', True):
    idx.equals(ks.Index(['a', 'b', 'c']))

[codecov-io]

Codecov Report

Merging #1216 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1216      +/-   ##
==========================================
- Coverage   95.21%   95.21%   -0.01%     
==========================================
  Files          35       35              
  Lines        7254     7252       -2     
==========================================
- Hits         6907     6905       -2     
  Misses        347      347

Impacted Files	Coverage Δ
databricks/koalas/missing/indexes.py	100% <ø> (ø)	⬆️
databricks/koalas/indexes.py	96% <100%> (ø)	⬆️

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[HyukjinKwon]

I am merging this for today's release.

[ueshin]

Why is this False? Also, for identical?

>>> import pandas as pd
>>> idx = pd.Index(['a', 'b', 'c'])
>>> idx.equals(idx)
True
>>> idx.identical(idx)
True

[ueshin]

Submitted a PR #1220.

[ueshin]

ditto.

>>> midx = pd.MultiIndex.from_tuples([('a', 'x'), ('b', 'y'), ('c', 'z')])
>>> midx.names = ("nameA", "nameB")
>>> midx.equals(midx)
True
>>> midx.identical(midx)
True