Respect RdMacros

[ManuelHentschel]

The help preview now respects Rd-macros, defined either in a local file or using the RdMacros entry in DESCRIPTION. To test, install e.g. the package RdPack, and create a package directory with:

• ./man/macros/someMacroFile.Rd containing

  \newcommand{\testmacro}{This is a test!}
  

• ./DESCRIPTION containing

  [...]
  RdMacros: RdPack
  

• ./man/someHelpFile.Rd containing

  [...]
  \testmacro{}
  \insertAllCited{}
  

Previewing this help file should include the expanded macros, i.e. "This is a test!" and "There are no references for Rd macro \insertAllCites on this help page."

Furthermore, failing to convert an Rd file to HTML now shows a warning message.

[renkun-ken]

LGTM Thanks!

[renkun-ken]

One more thing, would you like to fix the lintr complain at https://github.com/REditorSupport/vscode-R/actions/runs/3558811159/jobs/5977742141?