Add support for moves across root modules

What remains to be done:

[x] Replace the internal/format package with a new pkg/pretty
[x] Replace the -show-analysis flag with a new -verbosity flag
[x] Get the -no-color flag working again, and add support for NO_COLOR
[x] Add tests to the new pkg/engine package
[x] Add tests to the new pkg/terraform package (especially the Write* functions)
[x] Add tests to the new pkg/pretty package
[x] Add end-to-end tests for the cross-module feature
[x] Add smoke tests to catch invalid configuration ASAP (eg: multiple modules + moved blocks)

busser / tfautomv