This pull request contains a few changes:
1. Adds support for string ort values.
2. Fixes the training minimal build (that was broken with #16601) by
putting custom op registration behind #ifdefs
3. Fixes the iOS pod package generation (that was again broken with
#16601) by explicitly providing paths to be copied during pod creation.
### Description
Added support for int64 and uint64 in Objective-C lib.
### Motivation and Context
Int64 is rarely used, but we needed it. The Int64 inference worked after
the change (tested).
### Description
<!-- Describe your changes. -->
I fixed some broken links in the C API documentation, but then did a
quick pass over all of the links I could find and then fixed those.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
I got some 404's when exploring the documentation and wanted to fix it.
Update Objective-C API to be more usable from Swift. E.g., to allow conversion from Objective-C methods with trailing NSError** parameter to throwing Swift methods.
Update CMake Objective-C framework setup.
