Support scheme-agnostic projects (#486)

This adds changes to support loading project dependencies in non-file based projects.

The design for this feature can be found in SPICE-0005: https://github.com/apple/pkl-evolution/pull/6

Changes:
* Consider all imports prefixed with `@` as dependency notation.
* Bugfix: fix resolution of glob expressions in a local dependency.
* Adjust pkl.Project:
  - Allow local dependencies from a scheme-local paths.
  - Disallow certain evaluator settings if not loaded as a file-based module.
* Breaking API change: `ProjectDependenciesManager` constructor now requires `ModuleResolver` and `SecurityManager`.

pkl-core/src/main/resources/org/pkl/core/errorMessages.properties

@@ -542,6 +542,12 @@ Cannot combine glob imports with triple-dot module URIs.
 cannotGlobUri=\
 Cannot expand glob pattern `{0}` because scheme `{1}` is not globbable.
 
+cannotResolveInLocalDependencyNotGlobbable=\
+Cannot resolve import in local dependency because scheme `{0}` is not globbable.
+
+cannotResolveInLocalDependencyNotGlobbableNorLocal=\
+Cannot resolve import in local dependency because scheme `{0}` is not globbable and is not local.
+
 expectedAnnotationClass=\
 Expected an annotation class.
 
@@ -680,6 +686,11 @@ Cannot resolve a triple-dot import from module URI `{0}`.\n\
 \n\
 Triple-dot imports may only be resolved by module schemes that are considered local, and have hierarchical URIs.
 
+moduleDoesNotSupportDependencies=\
+Module `{0}` does not support importing dependencies.\n\
+\n\
+Dependencies can only be imported in modules that belong to a project, or within a package.
+
 cannotHaveRelativeImport=\
 Module `{0}` cannot have a relative import URI.
 
@@ -819,6 +830,9 @@ Only type unions can have a default marker (*).
 invalidModuleOutputValue=\
 Expected `output.value` of module `{2}` to be of type `{0}`, but got type `{1}`.
 
+cannotResolveDependencyWithoutHierarchicalUris=\
+Cannot import dependency because project URI `{0}` does not have a hierarchical path.
+
 cannotResolveDependencyNoProject=\
 Cannot import dependency because there is no project found.\n\
 \n\
@@ -830,6 +844,11 @@ Cannot find a dependency named `{0}`, because it is not declared in the current
 \n\
 To fix this, add it to the `dependencies` section of your `PklProject` file, and resolve your dependencies.
 
+cannotResolveDependencyFromReaderWithOpaqueUris=\
+Cannot resolve dependencies from module reader with opaque URIs.\n\
+\n\
+Module reader for scheme `{0}` does not support hierarchical URIs.
+
 cannotFindDependencyInPackage=\
 Cannot find dependency named `{0}`, because it was not declared in package `{1}`.
 
@@ -856,10 +875,10 @@ For example, `example.com` in URI `project://example.com/my/package@1.0.0`.
 unexpectedChecksumInPackageUri=\
 Did not expect to find a checksum component in this package URI.
 
-missingProjectDepsJson=\
-Cannot resolve dependency because file `PklProject.deps.json` is missing in project directory `{0}`.\n\
+cannotLoadProjectDepsJson=\
+Encountered an error when attempting to load `PklProject.deps.json` at `{0}`.\n\
 \n\
-Run `pkl project resolve` to create a new set of dependencies.
+Try running `pkl project resolve` within the project directory to create a new set of dependencies.
 
 invalidProjectDepsJson=\
 Cannot resolve dependency because file `{0}` is malformed.\n\
@@ -978,6 +997,16 @@ No package was declared in project `{0}`.\n\
 \n\
 Add a `package` section to the PklProject file.
 
+relativePathPropertyDefinedByProjectFromNonFileUri=\
+Invalid property specified in project `{0}`\n\
+\n\
+Property `{1}` is only permitted in PklProject files loaded from `file:` URIs.
+
+invalidUsageOfProjectFromNonFileUri=\
+Invalid usage of project `{0}`\n\
+\n\
+This action can only be performed with PklProject files loaded from `file:` URIs.
+
 packageTestsFailed=\
 Failed to create package `{0}`, because its API tests are failing.