Add GetHttpsCallableFromURL to Functions

[a-maurice]

Description

Provide details of the change, and generalize the change in the PR title above.

Adds GetHttpsCallableFromURL to the Functions SDK. This was recently added to both the Android and iOS SDKs.

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Testing

Describe how you've tested these changes. Link any manually triggered Integration tests or CPP binary SDK Packaging Github Action workflows, if applicable.

Running the testapps on mobile and desktop locally with the changes.

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Type of Change

Place an x the applicable box:

• Bug fix. Add the issue # below if applicable.
• New feature. A non-breaking change which adds functionality.
• Other, such as a build process or documentation change.

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Notes

• Bug fixes and feature changes require an update to the Release Notes section of release_build_files/readme.md.
• Read the contribution guidelines CONTRIBUTING.md.
• Changes to the public API require an internal API review. If you'd like to help us make Firebase APIs better, please propose your change in a feature request so that we can discuss it together.

[github-actions]

❌  Integration test FAILED

Requested by @a-maurice on commit a192efb
Last updated: Tue May 24 16:39 PDT 2022
View integration test log & download artifacts

Failures	Configs
admob	[BUILD] [ERROR] [Android] [1/3 os: windows]
analytics	[BUILD] [ERROR] [Android] [1/3 os: windows]
auth	[TEST] [FLAKINESS] [iOS] [macos] [1/2 ios_device: ios_target] (1 failed tests)   FirebaseAuthTest.TestUpdateEmailAndPassword
firestore	(4 items) [TEST] [ERROR] [Android] [All 3 os] [1/2 android_device: emulator_target] [TEST] [ERROR] [iOS] [macos] [1/2 ios_device: simulator_target] [TEST] [ERROR] [tvOS] [macos] [tvos_simulator] [TEST] [FLAKINESS] [Android] [1/3 os: macos] [1/2 android_device: android_target] (1 failed tests)   CRASH/TIMEOUT

Add flaky tests to go/fpl-cpp-flake-tracker

[a-maurice]

The failed tests seem to be flaky ones in Firestore, and unrelated to this change.