… in SparkR support 3L namespace

### What changes were proposed in this pull request?
add currentDatabase/setCurrentDatabase/listCatalogs

### Why are the changes needed?
to support 3L namespace in SparkR

### Does this PR introduce _any_ user-facing change?
yes, new API added

### How was this patch tested?
added UT

Closes #37127 from zhengruifeng/r_3L_catalog.

Authored-by: Ruifeng Zheng <ruifengz@apache.org>
Signed-off-by: Ruifeng Zheng <ruifengz@apache.org>