Add Metal API for GRBackendRenderTarget to all platforms

[spouliot]

Description of Change

Add public GRBackendRenderTarget (int width, int height, GRMtlTextureInfo mtlInfo) to the netXX builds.

Bugs Fixed

• Fixes [BUG] Missing GRBackendRenderTarget ctor for Metal #3069

API Changes

Added:

public GRBackendRenderTarget (int width, int height, GRMtlTextureInfo mtlInfo)

Behavioral Changes

None.

Required skia PR

None.

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Merged related skia PRs
• Changes adhere to coding standard
• Updated documentation

[mattleibow]

/azp run

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[mattleibow]

/azp run

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[github-actions]

The backport to release/3.116.0 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-release/3.116.0 release/3.116.0
# Navigate to the new working tree
cd .worktrees/backport-release/3.116.0
# Create a new branch
git switch --create backport/pr-3070-to-release/3.116.0
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 8afcbc41a289e55db42ea2a5da09b3e313900533
# Push it to GitHub
git push --set-upstream origin backport/pr-3070-to-release/3.116.0
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release/3.116.0

Then, create a pull request where the base branch is release/3.116.0 and the compare/head branch is backport/pr-3070-to-release/3.116.0.

[spouliot]

thanks @mattleibow !