Add `GDALVector::deleteFeature()`

[ctoney]

$deleteFeature(fid)

' Delete feature from layer. The feature with the indicated feature ID is

' deleted from the layer if supported by the format driver. The value of fid

' must be a numeric scalar, optionally carrying the bit64::integer64 class

' attribute (should be a whole number, will be truncated). The DeleteFeature

' element in the list returned by $testCapability() can be checked to

' establish if this layer has delete feature capability. Returns logical

' TRUE if the operation succeeds, or FALSE on failure.