[BUG] Texinfo: Commas in URL text are not escaped

[8dcc <8dcc.git@gmail.com>]

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Hello,

The following Org file:

  [[https://example.com][Foo]]

  [[https://example.com][Foo, Bar]]

When exported to Texinfo using `org-texinfo-export-to-texinfo',
generates the following file:

  ...
  @uref{https://example.com, Foo}

  @uref{https://example.com, Foo, Bar}
  ...

The comma on the text of the second URL is being interpreted by Texinfo
as an argument separator, which in the case of `@uref', only the third
argument is displayed, hiding the second argument and the actual URL
when exporting the file.


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Therefore, it should be escaped to `@comma{}', according to the Texinfo
manual[1]:

  ...
  @uref{https://example.com, Foo}

  @uref{https://example.com, Foo@comma{} Bar}
  ...

This produces the expected output.


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[1] Section 11.1.3, Inserting `,' with `@comma{}'.
    https://www.gnu.org/software/texinfo/manual/texinfo/html_node/Inserting-a-Comma.html

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