Docker build needs `platform` parameter defined

[Jandev]

The Container Registry likes to have a linux/amd64 image.
However, when running the scripts on a Macbook it gets build with the linux/arm64 platform by default resulting in the following error:

Updating Container App with new image...
- Running ..ERROR: Failed to provision revision for container app 'ca-web-grb345qzdhluq'. Error details: The following field(s) are either invalid or missing. Field 'template.containers.ca-web-grb345qzdhluq.image' is invalid with details: 'Invalid value: "crgrb345qzdhluq.azurecr.io/ai-foundry-agent/web-dev:azd-deploy-1764155623": image OS/Arc must be linux/amd64 but found linux/arm64';..
Write-Error: Container deployment failed: Container app update failed

I've added the --platform parameter in the build-and-deploy-container.ps1 file to fix this issue.

$dockerfilePath = Join-Path "deployment" "docker" "frontend.Dockerfile"
docker build `
    --platform linux/amd64 `
    --build-arg ENTRA_SPA_CLIENT_ID=$ClientId `
    --build-arg ENTRA_TENANT_ID=$TenantId `
    -f $dockerfilePath `
    -t $imageName `
    . 2>&1 | Out-Host

$buildOutput = az acr build `
    --registry $AcrName `
    --image "ai-foundry-agent/web-dev:$imageTag" `
    --platform linux/amd64 `
    --build-arg ENTRA_SPA_CLIENT_ID=$ClientId `
    --build-arg ENTRA_TENANT_ID=$TenantId `
    --file $dockerfilePath `
    --no-logs `
    . 2>&1