REST query should allow/respect configurable certificate path

[ihnorton]

Currently the REST/curl query path uses only the globally-detected certificate store:

https://github.com/TileDB-Inc/TileDB/blob/e651eb9c969c230fd42feb0911f108c7e6fba43b/tiledb/sm/rest/curl.cc#L210-L219

whereas the S3/curl request path allows configuration via the vfs.s3.ca_file/vfs.s3.ca_path parameters:

https://github.com/TileDB-Inc/TileDB/blob/4e4146d30fc1db4b78a7c6d915be37cba1b46b8e/tiledb/sm/filesystem/s3.cc#L250-L260

The REST path should allow a similar configuration, ideally with an eventual transition to a unified parameter name like vfs.ca_path/vfs.ca_file.