WIP: Add GHA workflow for checking valid HTML5 docs

[IndrajeetPatil]

To know more about new HTML5 check in R-devel, see: https://blog.r-project.org/2022/04/08/enhancements-to-html-documentation/

Workflow from: https://github.com/r-lib/actions/blob/v2-branch/examples/html-5-check.yaml

[IndrajeetPatil]

Issues unearthed by the new check:

❯ checking PDF version of manual ... ERROR
  Rd conversion errors:
  Converting Rd files to LaTeX .......Error : object_name_linter.Rd:11: there is no package called ‘lintr’

❯ checking S3 generic/method consistency ... WARNING
  Error: cannot source package code:
  'length = 3' in coercion to 'logical(1)'
  Execution halted
  See section ‘Generic functions and methods’ in the ‘Writing R
  Extensions’ manual.

❯ checking replacement functions ... WARNING
  Error: cannot source package code:
  'length = 3' in coercion to 'logical(1)'
  Execution halted
  The argument of a replacement function which corresponds to the right
  hand side must be named ‘value’.

❯ checking Rd files ... WARNING
  object_name_linter.Rd:11: there is no package called ‘lintr’
  problem found in ‘object_name_linter.Rd’

❯ checking for missing documentation entries ... WARNING
  Error: cannot source package code:
  'length = 3' in coercion to 'logical(1)'
  Execution halted
  All user-level objects in a package should have documentation entries.
  See chapter ‘Writing R documentation files’ in the ‘Writing R
  Extensions’ manual.

❯ checking R code for possible problems ... NOTE
  Error: cannot source package code:
  'length = 3' in coercion to 'logical(1)'
  Execution halted
  Error: cannot source package code:
  'length = 3' in coercion to 'logical(1)'
  Execution halted

❯ checking Rd \usage sections ... NOTE
  Error: cannot source package code:
  'length = 3' in coercion to 'logical(1)'
  Execution halted
  The \usage entries for S3 methods should use the \method markup and not
  their full name.
  See chapter ‘Writing R documentation files’ in the ‘Writing R
  Extensions’ manual.

❯ checking HTML version of manual ... NOTE
  Encountered the following conversion/validation errors:
  object_name_linter.Rd:11: there is no package called ‘lintr’

1 error ✖ | 4 warnings ✖ | 3 notes ✖