Comment folding for region has wrong syntax

[jthomasmock]

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I believe our folding needs to drop the // from the regex to allow the region feature to work. That's more of a javascript/typescript comment syntax.

https://github.com/posit-dev/positron/blob/3d8649a40f6613645a4d2ac8a55c1fb21d5ee851/extensions/positron-r/language-configuration/r-language-configuration.json#L29-L34

Compare it to Python:

https://github.com/posit-dev/positron/blob/3d8649a40f6613645a4d2ac8a55c1fb21d5ee851/extensions/python/language-configuration.json#L43-L48

In Python:

In R: