(GH-538) Set URI and docs keywords for DscRepoSchema types

[Mikey Lombardi (He/Him) (michaeltlombardi)]

PR Summary

This change:

1. Defines new extension methods for operating on schemars::Schema instances:

   • [get|set]_title - Retrieve and override the title keyword as a string slice.
   • [get|set]_description - Retrieve and override the description keyword as a string slice.
   • set_markdown_description - Override the markdownDescription keyword as a string slice.
   • [get|set]_meta_schema - Retrieve and override the $schema keyword as a string slice.
   • get_meta_schema_as_url - Retrieve the $schema keyword as a Url.
   • has_meta_schema_keyword - Indicate whether schema defines the $schema keyword.

2. Defines new transformer functions for the DscRepoSchema trait:

   • transform_export_schema_uris - Insert the $id and $schema keywords with the default_export_* function outputs.
   • transform_schema_docs - Insert the title, description, and markdownDescription keywords if they have defined localization strings.
   • transform_schema_docs_strict - Insert the title, description, and markdownDescription keywords if they have defined localization strings. If any translation strings are missing, panic.

3. Updates the type definitions in dsc-lib for every type that derives or implements DscRepoSchema to ensure that the $id and $schema keywords are always populated and the docs keywords are defined if the translation strings are provided. Where the type was already using translated docs this change uses the strict transform to catch regressions in translation string definitions.

PR Context

Prior to this change the generated schemas were not consistently defining the $id and $schema keywords, which we need to properly populate for every schema that we publish in its own file. Additionally, the documentation keywords were manually inserted for every schema (that has translated docs already defined).

Effectively, before this PR, every struct needed a definition like the following when deriving JsonSchema and DscRepoSchema:

#[derive(Debug, Clone, JsonSchema, DscRepoSchema)]
#[dsc_repo_schema(base_name = "struct", folder_path = "example")]
#[schemars(
    title = schema_i18n!("title"),
    description = schema_i18n("description"),
    extend(
        "$schema" = ExampleStruct::default_export_meta_schema_uri(),
        "$id"     = ExampleStruct::default_export_schema_id_uri(),
        "markdownDescription" = schema_i18n!("markdownDescription"),
    )
)]
pub struct ExampleStruct {
    // Elided for brevity
}

With these changes, the definition now looks like:

#[derive(Debug, Clone, JsonSchema, DscRepoSchema)]
#[dsc_repo_schema(base_name = "struct", folder_path = "example")]
#[schemars(
    transform = ExampleStruct::transform_export_schema_uris,
    transform = ExampleStruct::transform_schema_docs,
)]
pub struct ExampleStruct {
  // Elided for brevity
}

This corrects various problems in the schema generation and export pipeline, which relies on the $id keyword to correctly manage bundled schema resources, and ensures that we can update the docs keywords for types without needing to modify the type definition directly.