Add broadcasting tests (CI not passed yet)

[tk3369]

Added v0.21.7 broadcasting.jl tests
https://raw.githubusercontent.com/JuliaData/DataFrames.jl/v0.21.7/test/broadcasting.jl

CI not passed yet:

Test Summary:                                                                   | Pass  Fail  Error  Total
AbstractWrappedDataFrame                                                        |  911    13      9    933
  Basic Operations                                                              |   52                  52
  CartesianIndex                                                                |                 2      2
  broadcasting of AbstractDataFrame objects                                     |   28                  28
  broadcasting of AbstractDataFrame objects thrown exceptions                   |   10                  10
  broadcasting expansion                                                        |    5                   5
  broadcasting of AbstractDataFrame objects corner cases                        |   34                  34
  normal data frame and data frame row in broadcasted assignment - one column   |  117                 117
  normal data frame and data frame view in broadcasted assignment - two columns |  104                 104
  assignment to a whole data frame and data frame row                           |    8                   8
  extending data frame in broadcasted assignment - one column                   |   18     1      1     20
  empty data frame corner case                                                  |    4     8      1     13
  test categorical values                                                       |  126                 126
  scalar broadcasting                                                           |    3                   3
  tuple broadcasting                                                            |    8                   8
  scalar on assignment side                                                     |    4                   4
  nothing test                                                                  |    3            1      4
  aliasing test                                                                 |  154                 154
  @. test                                                                       |    2                   2
  test common cases                                                             |   11                  11
  data frame only on left hand side broadcasting assignment                     |   26                  26
  broadcasting with 3-dimensional object                                        |    3            1      4
  additional checks of post-! broadcasting rules                                |  168                 168
  DataFrameRow getproperty broadcasted assignment                               |    8                   8
  make sure that : is in place and ! allocates                                  |    6     4            10
  add new correct rules for df[row, col] .= v broadcasting                      |    5            1      6
  broadcasting into df[!, cols]                                                 |                 1      1
  broadcasting over heterogenous columns                                        |    1                   1
  @views on df[!, col]                                                          |    3                   3
  broadcasting of df[:, col] = value                                            |                 1      1
ERROR: LoadError: Some tests did not pass: 911 passed, 13 failed, 9 errored, 0 broken.
in expression starting at /Users/tomkwong/Julia/AbstractWrappedDataFrames/test/runtests.jl:3
ERROR: Package AbstractWrappedDataFrames errored during testing

[tk3369]

@bkamins It's probably something else more than just defining Base.broadcastable. It looks like other things are broken as unrelated to broadcasting. See CI failure here https://travis-ci.com/github/tk3369/AbstractWrappedDataFrames.jl/builds/185558174.

[bkamins]

After adding Base.broadcasted you should check with e.g. @code_warntype how the expression is being transformed - this should show where the problem is.