[release/7.0] [wasm] Add warning code to all warnings produced in WasmAppBuilder

[github-actions]

Backport of #78755 to release/7.0

/cc @maraf

Customer Impact

Customers can disable individual warnings that can occur while building wasm applications.
Fixes customer reported issue #78690.

Testing

Manual.

Risk

Low. Only warning codes where added to existing warnings.

IMPORTANT: Is this backport for a servicing release? If so and this change touches code that ships in a NuGet package, please make certain that you have added any necessary package authoring and gotten it explicitly reviewed.

[ghost]

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Backport of #78755 to release/7.0

/cc @maraf

Customer Impact

Customers are able to disable indivial warnings that can occur while building wasm applications.
Fixes customer reported issue #78690.

Testing

Manual.

Risk

Low. The only change without additional configuration is that warning messages are prefixed with warning code.

IMPORTANT: Is this backport for a servicing release? If so and this change touches code that ships in a NuGet package, please make certain that you have added any necessary package authoring and gotten it explicitly reviewed.

Author:	github-actions[bot]
Assignees:	-
Labels:	arch-wasm, area-Build-mono
Milestone:	7.0.x

[carlossanlop]

Approved by Tactics.
Signed off by area owner.
No OOB changes needed.
CI failure is known, unrelated, and has already been fixed in the branch: #78778
Waiting for the last question to be answered before merging.

[carlossanlop]

Although there's still an additional question to answer in the conversation, it was marked as resolved, so I'll merge.

CI failure is known/unrelated/already fixed: #78778