syntax: escaped backticks not handled in identifier

[kevinushey]

For example, the following is a valid identifier:

`\``

But the escaped backtick is treated as the end of the identifier, and so the final backtick is its own separate thing.

https://github.com/REditorSupport/vscode-R/blob/da579cc17a9485f7a11bf5e75bf6b9c347eca116/syntax/r.json#L169-L172

I think a regular expression like the following would suffice:

([`](?:(?:\\\\.)|(?:[^`\\\\]))*[`])

Alternatively, I think the existing strategy for matching strings could be re-used for quoted identifiers.

https://github.com/REditorSupport/vscode-R/blob/da579cc17a9485f7a11bf5e75bf6b9c347eca116/syntax/r.json#L315-L335

[github-actions]

This issue is stale because it has been open for 365 days with no activity.

[eitsupi]

unstale

[github-actions]

This issue is stale because it has been open for 365 days with no activity.

[ThomasSoeiro]

@eitsupi Can you please transfer to vscode-R-syntax?