fix: [OData] Revert mutability of ODataResourcePath and resolve segment duplication

[rpanackal]

Context

SAP/cloud-sdk-java-backlog#ISSUENUMBER.

Fix for regression in #1121.

Previously known issue: InCountRequestBuilder.toRequest(): calling toRequest() twice on the same builder would produce corrupted paths like Trips/$count/$count instead of Trips/$count

The original pull request resolved the issue by making ODataResourcePath immutable.

But by doing so, code that relied on mutability of ODataResourcePath failed silently.

ODataResourcePath path = new ODataResourcePath();
path.addSegment("A_BusinessPartner");  // return value discarded

// Next `someMethod(path)` call, don't pass along the expected segment "A_BusinessPartner"

Feature scope:

• Introduce a public copy() method in ODataResourcePath for defensive copy
  • Not advertised in release notes
• ODataRequestRead, ODataRequestCount, ODataRequesReadByKey, ODataRequestFunction and ServiceWithNavigableEntitiesImpl now create a defensive copy before respective operation.

Definition of Done

• Functionality scope stated & covered
• Tests cover the scope above
• Error handling created / updated & covered by the tests above
• Documentation updated
• Release notes updated

[newtork]

Looks good! Please add @Beta annotation and @since tag :)

[Jonas-Isr]

lgtm