## Changes
This is similar to #904 but instead of converting the dynamic
configuration to Go structs, this normalizes a `config.Value` according
to the type of a Go struct and returns the new, normalized
`config.Value`.
This will be used to ensure that two `config.Value` trees are
type-compatible before we can merge them (i.e. instances from different
files).
Warnings and errors during normalization are accumulated and returned as
a `diag.Diagnostics` structure. We can use this to surface warnings
about unknown fields, or errors about invalid types, in aggregate
instead of one-by-one. This approach is inspired by the pattern to
accumulate diagnostics in Terraform provider code.
## Tests
New unit tests.
Pieter Noordhuis