feat(vm): sort package files AddPackage

[waymobetta]

WIP/untested.

This PR introduces sorting of files during vm.AddPackage ensuring that the vm processes files in accordance with Go's lexical conventions.

Related: #1482

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.