This :
* allows to have a `build.dynamic` block
* add tests
* makes sure to show a correct message when a source was not found
* display only name of source (instead of a weird map printout)
* use a "Did you mean %q" feature where possible
Because dynamic blocks need all variables to be evaluated and available, I moved parsing of everything that is not a variable to "after" variables are extrapolated. Meaning that dynamic block get expanded in the `init` phase and then only we start interpreting HCL2 content.
After #10819fix#10657