Change runtime SiteExtension to replace AspNetCoreModuleV2 definition

[pakrym]

Epic #8833

Currently, the module is only inserted when missing and it's always present since it was deployed to AppServices.

We need to change xdt to use Replace transformation.

This is blocked by AppService having protection from changing default global module location. They have been contacted and are going to relax the rule for AspNetCoreModuleV2, ETA March'19.

[pakrym]

@shirhatti

[muratg]

Triage notes:
Revisit once Antares fix is out. We need to update the site extension

[analogrelay]

We need to revisit this since we believe the Antares fix is out.