prepare the transition to #Plan.context

This change helps the transition between `dagger input` and `#Plan.context`.

In summary, the codebase now relies on a *context* for execution with mapping to *IDs*.
In the future, *context* will come from a `#Plan.context`.
In the meantime, a bridge converts `dagger input` to a plan context. This allows both *old* and *new* style configurations to co-exist with the same underlying engine.

- Implement `plancontext`. Context holds the execution context for a plan. Currently this includes the platform, local directories, secrets and services (e.g. unix/npipe).
- Contextual data can be registered at any point. In the future, this will be done by `#Plan.context`
- Migrated the `dagger input` codebase to register inputs in a `plancontext`
- Migrated low-level types/operations to the *Context ID* pattern.
  - `dagger.#Stream` now only includes an `id` (instead of `unix` path)
  - `dagger.#Secret` still includes only an ID, but now it's based off `plancontext`
  - `op.#Local` now only includes an `id` (instead of `path`, `include`, `exclude`.

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

state/state.go

@@ -6,10 +6,15 @@ import (
 
 	"cuelang.org/go/cue"
 	"go.dagger.io/dagger/compiler"
+	"go.dagger.io/dagger/plancontext"
 )
 
 // Contents of an environment serialized to a file
 type State struct {
+	// Plan Context.
+	// FIXME: this is used as a bridge and is temporary.
+	Context *plancontext.Context `yaml:"-"`
+
 	// State path
 	Path string `yaml:"-"`
 
@@ -67,7 +72,7 @@ func (s *State) CompileInputs() (*compiler.Value, error) {
 
 	// Prepare inputs
 	for key, input := range s.Inputs {
-		i, err := input.Compile(key, s)
+		i, err := input.Compile(s)
 		if err != nil {
 			return nil, err
 		}