Enable prefast and warnings checker in SDL

[DefaultRyan]

More compliance work, this time enabline prefast and the compiler warnings checker.

While I was here I also noticed that the visualizer was overriding SDL to disabled, so went ahead and removed that to allow the default "Enabled" value to prevail again.

PR Overview

This PR enables prefast and compliant compiler warnings checking in the SDL pipelines while also reverting the override in the visualizer so that SDL remains enabled by default. Key changes include adding new YAML keys to enable prefast and warning checks in job pipelines and updating the global SDL configuration in official and pull request pipelines.

Reviewed Changes

File	Description
.pipelines/jobs/OneBranchNuGet.yml	Added keys to enable prefast and warning checks
.pipelines/jobs/OneBranchBuild.yml	Added keys to enable prefast and warning checks
.pipelines/jobs/OneBranchTest.yml	Added keys to enable prefast and warning checks
.pipelines/OneBranch.Official.yml	Enabled prefast in the global SDL config and marked native code
.pipelines/jobs/OneBranchVsix.yml	Added keys to enable prefast and warning checks
.pipelines/OneBranch.PullRequest.yml	Enabled prefast in the global SDL config for pull requests

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (3)

.pipelines/jobs/OneBranchNuGet.yml:21

• [nitpick] The key 'ob_sdl_prefast_runDuring' uses mixed casing; consider using a consistent snake_case naming (e.g., 'ob_sdl_prefast_run_during') to improve readability.

ob_sdl_prefast_runDuring: 'Build'

.pipelines/OneBranch.Official.yml:44

• [nitpick] The global SDL configuration uses a nested 'prefast' block while the job pipelines use flat keys (e.g., ob_sdl_prefast_enabled). Consider aligning these naming conventions for consistency across configurations.

prefast:

.pipelines/OneBranch.PullRequest.yml:40

• [nitpick] The 'prefast' block in the global SDL configuration here is inconsistent with the flat key approach in job YAML files; consider standardizing the naming style to avoid potential confusion.

prefast: