[FEA] Include a SettingWithCopyWarning similar to pandas

[beckernick]

Users sometimes attempt to set a value on dataframe slices that are actually copies of the original dataframe. This does not usually error, but instead often silently results in downstream results being incorrect. This is common enough in pandas that they've included a warning to inform users of when this is happening. We should explore implementing something similar.

import pandas as pd

df = pd.DataFrame({'a':range(5)})
df[df['a'] >= 3]['a'] = 100
df
...: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
  after removing the cwd from sys.path.
   a
0  0
1  1
2  2
3  3
4  4

See this portion of the pandas codebase for more information.

[vyasr]

copy-on-write is available as of pandas 2.0 and will become the default in pandas 3.0. This feature is also available in cudf #12011. With copy-on-write, the need for the SettingWithCopyWarning goes away. Given that this is the (not too distant) future, there is no need to mirror this behavior in cudf since it has a clear timeline to be removed from pandas.