Remove SparseSeries and SparseDataFrame
As discussed on the dev call.

Closes https://github.com/pandas-dev/pandas/issues/28407
Closes https://github.com/pandas-dev/pandas/issues/28025
Closes https://github.com/pandas-dev/pandas/issues/26777
Closes https://github.com/pandas-dev/pandas/issues/26227
~Not https://github.com/pandas-dev/pandas/issues/26123~
Closes https://github.com/pandas-dev/pandas/issues/25694
Closes https://github.com/pandas-dev/pandas/issues/25378
~Not https://github.com/pandas-dev/pandas/issues/25270~
~Not https://github.com/pandas-dev/pandas/issues/24817~
Closes https://github.com/pandas-dev/pandas/issues/24270
Closes https://github.com/pandas-dev/pandas/issues/22630
Closes https://github.com/pandas-dev/pandas/issues/21993
Closes https://github.com/pandas-dev/pandas/issues/21909
~Not https://github.com/pandas-dev/pandas/issues/21818~
Closes https://github.com/pandas-dev/pandas/issues/21231
Closes https://github.com/pandas-dev/pandas/issues/20766
Closes https://github.com/pandas-dev/pandas/issues/20172
~Not https://github.com/pandas-dev/pandas/issues/19278~
Closes https://github.com/pandas-dev/pandas/issues/18969
~Not https://github.com/pandas-dev/pandas/issues/18414~
Closes https://github.com/pandas-dev/pandas/issues/17993
Closes https://github.com/pandas-dev/pandas/issues/15737
Closes https://github.com/pandas-dev/pandas/issues/15634
Closes https://github.com/pandas-dev/pandas/issues/14427
Closes https://github.com/pandas-dev/pandas/issues/14310
Closes https://github.com/pandas-dev/pandas/issues/13665
~Not https://github.com/pandas-dev/pandas/issues/11726~
Closes https://github.com/pandas-dev/pandas/issues/10627
Closes https://github.com/pandas-dev/pandas/issues/9275
~Not https://github.com/pandas-dev/pandas/issues/9265~
Closes https://github.com/pandas-dev/pandas/issues/6427
Closes https://github.com/pandas-dev/pandas/issues/5470
Closes https://github.com/pandas-dev/pandas/issues/5078
