Fix BasicRequestsTest.testReadSelectPartial for nesting-preserving field projection

[vharseko]

Summary

After the commons change OpenIdentityPlatform/commons@3bb9a67 that makes Resources.filterResource preserve the
nested structure of requested fields (see OpenIDM discussion
#183), the
opendj-rest2ldap test BasicRequestsTest.testReadSelectPartial started
failing. This PR updates the test assertions to match the corrected,
nesting-preserving projection behavior.

Background

Previously, Resources.filterResource(JsonValue, Collection<JsonPointer>)
collapsed a nested pointer (e.g. name/surname) to its leaf name, producing a
flat result like { "surname": "user 1" }. The commons fix now writes each
requested pointer back under its full path via JsonValue.putPermissive(...),
so the same read returns:

{ "name": { "surname": "user 1" } }

Problem

testReadSelectPartial still asserted the old flattening behavior and failed
with:

java.lang.AssertionError: <{'surname'='user 1'}> should be null
    at org.forgerock.opendj.rest2ldap.BasicRequestsTest.testReadSelectPartial(BasicRequestsTest.java:808)

This is not a regression in production code — the test was encoding the very
behavior that the commons fix corrected.

Changes

Updated the assertions in testReadSelectPartial
(opendj-rest2ldap/src/test/java/org/forgerock/opendj/rest2ldap/BasicRequestsTest.java)
to reflect the nesting-preserving projection:

• get("name").asMap() is now expected to be non-null.
• The value is read via the nested path name/surname ("user 1").
• The top-level surname field is now expected to be null.

No production code was changed.

Testing

mvn -pl opendj-rest2ldap test -Dtest=BasicRequestsTest

All 57 tests in BasicRequestsTest pass.