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ARROW-5117: [Go] fix panic when nil or empty slices are appended to builders

Author: Sebastien Binet <binet@cern.ch>

Closes #4131 from sbinet/issue-5117 and squashes the following commits:

ed94f049 <Sebastien Binet> arrow/array: rename TestStringArray_Empty into TestStringBuilder_Empty
bbd0a252 <Sebastien Binet> arrow/array: reorder Append nils in builder tests
3dcfc56a <Sebastien Binet> array: add tests for binary, boolean, fixedsize and string arrays
9599df01 <Sebastien Binet> array: generate numeric builder tests
662d18eb <Sebastien Binet> arrow/array: consistently use defers for builders' Release
9fc9bd99 <Sebastien Binet> ARROW-5117:  fix panic when nil or empty slices are appended to builders