Correct tiledb_query_get_range_var call

[eddelbuettel]

This small PR corrects a minor yet subtle copy-and-paste-and-forgot-to-edit error uncovered by a new code parsing tool from @dmurdoch which @kurthornik ran at CRAN and kindly emailed me about. The (R-level) accessor for the API query function for a variable length (i.e., string) buffer was only copied over from the fixed size and lacked the trailing four characters _var resulting in a twice-defined function where one shadows the other. Nice tricks one can play when computing on the language, and well spotted!

Minimal change made, documentation header altered, resulting changes also affect NAMESPACE as they should and Rd files. Small (and hitherto missing) test section added as well.

[shortcut-integration]

This pull request has been linked to Shortcut Story #41552: Correct tiledb_query_get_range for variable length case.

[eddelbuettel]

For completeness:

[aaronwolen]

Wow, nice catch.