Remove the option to pass data types as strings to read_csv and read_json

[vuule]

closes #8240

Also added a missing check for dtype count to the JSON reader and negative tests for the check.

[codecov]

Codecov Report

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@@               Coverage Diff               @@
##             branch-21.10    #9079   +/-   ##
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  Coverage                ?   10.71%           
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  Files                   ?      114           
  Lines                   ?    18701           
  Branches                ?        0           
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  Hits                    ?     2003           
  Misses                  ?    16698           
  Partials                ?        0           

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[vuule]

@gpucibot merge