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>
