[Deprecation] `ldapname` Fact Option and Accessor

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Summary

ldapname on custom facts is deprecated and logs a warning that it will be removed.

Evidence

• lib/facter/custom_facts/util/fact.rb:21 marks ldapname accessor as deprecated.
• lib/facter/custom_facts/util/fact.rb:146 marks extract_ldapname_option! as deprecated.
• lib/facter/custom_facts/util/fact.rb:150 logs: ldapname is deprecated and will be removed in a future version.
• spec/custom_facts/util/fact_spec.rb:53 asserts the deprecation warning.

Proposed Change

• Remove attr_accessor :ldapname from Facter::Util::Fact.
• Remove option extraction for :ldapname.
• Remove collection-level forwarding to extract_ldapname_option! (lib/facter/custom_facts/util/collection.rb:166).

Compatibility / Risk

• Medium risk for custom facts that still pass ldapname: or read fact.ldapname.
• Behavior is already flagged at runtime; this is a planned hard removal.

Implementation Notes

• Remove warning path after API removal.
• Update tests that assert warning behavior to assert unsupported option behavior.
• Document migration: use fact name and modern custom fact metadata instead of LDAP-specific aliasing.

Acceptance Criteria

• ldapname is no longer accepted as a fact option.
• Facter::Util::Fact no longer exposes ldapname.
• No deprecation warning about ldapname remains in runtime logs.

Suggested Tests

• Unit test that ldapname: option is rejected or ignored per final policy.
• Unit test that no ldapname accessor is present.

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Deprecated in 757b458.