Extract the list of files and packages on ospacks and images

Generate pkglist and filelist files indexing the contents of each artifact so you don't need to download, decompress and mount just to check what is being shipped.

This MR includes:

• ad22cbe7 images: Extract the list of packages
• 0d7785cb images: Extract the list of files
• be185072 ospack: Rework pkglist and filelist extraction
• 9b12bd18 ospack,sysroot: Append file extension automatically

added 1 commit

• 60e80f00 - images: Extract the list of packages

Compare with previous version

resolved all discussions

added 4 commits

• e90c88cb - ospack,sysroot: Append file extension automatically
• 4f268d89 - ospack: Rework pkglist and filelist extraction
• 68a4d188 - images: Extract the list of files
• a150a497 - images: Extract the list of packages

Compare with previous version

added 4 commits

• 95eb77c1 - ospack,sysroot: Append file extension automatically
• 79420ff6 - ospack: Rework pkglist and filelist extraction
• 03c8e8a0 - images: Extract the list of files
• df0d76c8 - images: Extract the list of packages

Compare with previous version

added 6 commits

• df0d76c8...14384986 - 2 commits from branch master
• e1f04718 - ospack,sysroot: Append file extension automatically
• 390fcafc - ospack: Rework pkglist and filelist extraction
• 48d70bf0 - images: Extract the list of files
• 282a2eaa - images: Extract the list of packages

Compare with previous version

merged

for future reference please use -}} here; see https://golang.org/pkg/text/template/#hdr-Text_and_spaces for background

Good point, it would be more robust in case someone adds an unwanted space after the templatized variable and before the .tar.gz.