[r] Repace $attributes() accessor with one that uses libtiledbsoma (#3834)

Replace `TileDBArray$attributes()` with new
`SOMAArrayBase$attributes()`; this method uses a libtiledbsoma/Rcpp
function rather than `tiledb::attrs()` and returns a named list instead
of a tiledb-r wrapper around external pointers

[SC-64814](https://app.shortcut.com/tiledb-inc/story/64814)

continues work for #2406

Author: mojaveazure

apis/r/R/RcppExports.R

@@ -246,6 +246,10 @@ c_allows_dups <- function(uri, ctxxp) {
     .Call(`_tiledbsoma_c_allows_dups`, uri, ctxxp)
 }
 
+c_attributes <- function(uri, ctxxp) {
+    .Call(`_tiledbsoma_c_attributes`, uri, ctxxp)
+}
+
 resize <- function(uri, new_shape, function_name_for_messages, check_only, ctxxp) {
     .Call(`_tiledbsoma_resize`, uri, new_shape, function_name_for_messages, check_only, ctxxp)
 }

apis/r/R/SOMAArrayBase.R

@@ -16,6 +16,30 @@ SOMAArrayBase <- R6::R6Class(
     #'
     allows_duplicates = \() c_allows_dups(self$uri, private$.soma_context),
 
+    #' @description Retrieve the array attributes
+    #'
+    #' @return A named list of array attributes; each entry contains the
+    #' following named entries:
+    #' \itemize{
+    #'  \item \dQuote{\code{name}}: name of the attribute
+    #'  \item \dQuote{\code{type}}: datatype of the attribute
+    #'  \item \dQuote{\code{ncells}}: number of values per dimension cell
+    #'  \item \dQuote{\code{nullable}}: is the attribute nullable
+    #'  \item \dQuote{\code{filter_list}}: a list with filter information; this
+    #'   list contains the following entries:
+    #'   \itemize{
+    #'    \item \dQuote{\code{filter_type}}
+    #'    \item \dQuote{\code{compression_level}}
+    #'    \item \dQuote{\code{bit_width}}
+    #'    \item \dQuote{\code{positive_delta}}
+    #'    \item \dQuote{\code{float_bytewidth}}
+    #'    \item \dQuote{\code{float_factor}}
+    #'    \item \dQuote{\code{float_offset}}
+    #'   }
+    #' }
+    #'
+    attributes = \() c_attributes(self$uri, private$.soma_context),
+
     #' @description Is an array sparse?
     #'
     #' @return \code{TRUE} if the underlying TileDB array is sparse;

apis/r/man/SOMAArrayBase.Rd

@@ -576,6 +576,18 @@ BEGIN_RCPP
     return rcpp_result_gen;
 END_RCPP
 }
+// c_attributes
+Rcpp::List c_attributes(const std::string& uri, Rcpp::XPtr<somactx_wrap_t> ctxxp);
+RcppExport SEXP _tiledbsoma_c_attributes(SEXP uriSEXP, SEXP ctxxpSEXP) {
+BEGIN_RCPP
+    Rcpp::RObject rcpp_result_gen;
+    Rcpp::RNGScope rcpp_rngScope_gen;
+    Rcpp::traits::input_parameter< const std::string& >::type uri(uriSEXP);
+    Rcpp::traits::input_parameter< Rcpp::XPtr<somactx_wrap_t> >::type ctxxp(ctxxpSEXP);
+    rcpp_result_gen = Rcpp::wrap(c_attributes(uri, ctxxp));
+    return rcpp_result_gen;
+END_RCPP
+}
 // resize
 std::string resize(const std::string& uri, Rcpp::NumericVector new_shape, std::string function_name_for_messages, bool check_only, Rcpp::XPtr<somactx_wrap_t> ctxxp);
 RcppExport SEXP _tiledbsoma_resize(SEXP uriSEXP, SEXP new_shapeSEXP, SEXP function_name_for_messagesSEXP, SEXP check_onlySEXP, SEXP ctxxpSEXP) {
@@ -866,6 +878,7 @@ static const R_CallMethodDef CallEntries[] = {
     {"_tiledbsoma_c_schema", (DL_FUNC) &_tiledbsoma_c_schema, 2},
     {"_tiledbsoma_c_is_sparse", (DL_FUNC) &_tiledbsoma_c_is_sparse, 2},
     {"_tiledbsoma_c_allows_dups", (DL_FUNC) &_tiledbsoma_c_allows_dups, 2},
+    {"_tiledbsoma_c_attributes", (DL_FUNC) &_tiledbsoma_c_attributes, 2},
     {"_tiledbsoma_resize", (DL_FUNC) &_tiledbsoma_resize, 5},
     {"_tiledbsoma_resize_soma_joinid_shape", (DL_FUNC) &_tiledbsoma_resize_soma_joinid_shape, 4},
     {"_tiledbsoma_tiledbsoma_upgrade_shape", (DL_FUNC) &_tiledbsoma_tiledbsoma_upgrade_shape, 5},