--field-selector in gdal vector change-field-type instead of --field-name + --src-field-type ?

[rouault]

This is not the only place in the CLI where we need to perform some operation on a subset of fields (an obvious one is gdal vector select.) I think a more consistent and powerful alternative to this PR would be to define a set of selectors (FieldTypeIs(DateTime), FieldNameStartsWith(abc), etc. ) that can be applied to a set of OGRFieldDefn and then used anywhere that we need to select a set of fields.

Originally posted by @dbaston in https://github.com/OSGeo/gdal/issues/13092#issuecomment-3309220964