remove hard-coded image refs

[gainsley]

The code had hard-coded references to images:

• hard-coded version for vm base image (could be overridden per cloudlet, but we want default defined by the deployment)
• hard-coded reference to envoy-with-curl and nginx-with-curl images.

The full references to the images are now taken as command line arguments to CCRM, which then puts them into PlatformConfig, which is then used to generate CRM command line arguments.

[gainsley]

Looks good. Just a clarification on base image version. Right now if we set VmImageVersion for the cloudlet to 5.1.0 for instance it will try to boot pf/sharedLb with edgecloud-5.1.0 image. Is my understanding correct that now we need to set VmImageVersion to edgecloud-5.1.0?

Thanks for reviewing, Lev! vmImageVersion isn't being used anymore. cloudletVmImagePath is the full path to the file, including any version name as part of the directory path or the filename. We used to do this song-and-dance where the path root, the filename, and the version were all specified separately and concatenated together, but that was too confusing. There's now just the full path, and the md5sum.