improve docker image script

[lugehorsam]

• Fix error-handling in trap {} statement by changing it to a try...catch
  • If the script hit an error before $repoRootDir = Get-Location was invoked, the error would get masked by another error from within the trap handler

- InvalidOperation: C:\Users\lgehorsam\example\platform\windows_x64\docker\build.ps1:28:16
Line |
  28 |    Set-Location $repoRootDir
     |                 ~~~~~~~~~~~~
     | The variable '$repoRootDir' cannot be retrieved because it has not been set.

• Remove reference to previous windows container image.
• Fix repository root path test
• Change URI where build tools are pulled from.

[anfelbar]

Is this because of security reasons?

[anfelbar]

Oh wait. It looks like we don't run against windows (I think we did before)

[jayconrod]

Please keep this: it's not an example, it's meant to be used in production, even if we're not doing that right now.

[jayconrod]

Please keep this: it's not an example, it's meant to be used in production, even if we're not doing that right now.

[jayconrod]

This is based on an internal script docker_build.ps1. Let's keep these in sync. Please update that one first and verify docker build works.