Merge branch 'rf/fslsub' into 'master'

Add fsl.wrappers.fsl_sub, deprecate fsl.utils.fslsub.submit

Closes #376 and #373

See merge request fsl/fslpy!309
5 jobs for master in 68 minutes and 59 seconds (queued for 7 seconds)
Status Name Job ID Coverage
  Test
passed test:3.7 #49673
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00:13:13

94.0%
passed test:3.8 #49674
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00:13:54

94.0%
canceled test:3.9 #49675
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01:08:58

passed test:build-pypi-dist #49676
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00:01:28

 
  Style
canceled style #49677
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