[minor][feature]: Import bridging header according to where common-core is a submodule

[ameyapat]

PR Title Format

Required Format: [Keyword1] [Keyword2]: Description

• Keyword1: major, minor, or patch (case-insensitive)
• Keyword2: feature, bugfix, engg, or tests (case-insensitive)

Examples:

• [MAJOR] [Feature]: new API
• [minor] [bugfix]: fix crash
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Proposed changes

Xcode generates bridging header for swift classes to be available in Objective C classes in derived data. The obj C classes must import this header when using the swift classes. If common-core is a submodule in MSAL, it should import MSAL-Swift.h and if in oneAuth, it should import oneAuth-Swift.h

This PR adds a header that makes that determination during pod creation in a common header.

Type of change

• Feature work
• Bug fix
• Documentation
• Engineering change
• Test
• Logging/Telemetry

Risk

• High – Errors could cause MAJOR regression of many scenarios. (Example: new large features or high level infrastructure changes)
• Medium – Errors could cause regression of 1 or more scenarios. (Example: somewhat complex bug fixes, small new features)
• Small – No issues are expected. (Example: Very small bug fixes, string changes, or configuration settings changes)

Additional information

[Copilot]

Pull request overview

Adds a common header to abstract which generated Swift-to-Objective-C header (*-Swift.h) should be imported when common-core is consumed as a submodule (IdentityCore standalone vs inside MSAL/oneAuth), and wires JWE decryption ObjC code to use it.

Changes:

• Introduce MSIDSwiftBridgingHeader.h to select the correct *-Swift.h import via build macros.
• Update JWE decryption Objective-C code to import the new bridging header and call the Swift decryptor via a new ObjC selector.
• Expose Swift classes to Objective-C (and tweak Xcode build settings) to ensure Swift implementations are reachable from ObjC.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
changelog.txt	Adds an entry describing the new bridging-header selection behavior.
IdentityCore/src/util/MSIDConcatKdfProvider.swift	Adds ObjC exposure annotation to make the Swift KDF provider usable from ObjC.
IdentityCore/src/MSIDSwiftBridgingHeader.h	New shared header that conditionally imports the correct generated *-Swift.h.
IdentityCore/src/JWEResponse/MSIDJweResponse+EcdhAesGcm.m	Switches to the shared bridging header and updates the Swift decryptor call-site.
IdentityCore/src/JWEResponse/MSIDAesGcmDecryptor.swift	Adds ObjC exposure and a custom ObjC selector for the decrypt method.
IdentityCore/src/IdentityCore_Internal.h	Removes the MSID_IDENTITYCORE_SWIFT_AVAILABLE macro block.
IdentityCore/IdentityCore.xcodeproj/project.pbxproj	Registers the new header and enables installing the generated ObjC header for iOS configs.

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[Copilot]

@ameyapat I've opened a new pull request, #1679, to work on those changes. Once the pull request is ready, I'll request review from you.