Support parsing of Arazzo definitions

[paulRbr]

This PR is dedicated to Arazzo parsing in the current API class
(which name is incorrect and should be renamed Definition in a later
PR...).

It's a combination of multiples commits which should be reviewable
individually, but they stand as a whole. That's why I opened a PR with
all the commits.

Mainly the PR does:

• Support Arazzo definition in the API class, allowing to do
  API.load(arazzoFile) with errors
• Quite a few refactos in this API (definition.ts) class to make
  improve the intent of some private functions
• Extract arazzo's sourceDescriptions when extracting an Arazzo
  typed definition.

Once this is merged, and the bump.sh workflow deploy API is changed to
accept a list of references (the source descriptions), we will be able to change the API client layer:

modified   src/api/models.ts
@@ -82,6 +82,9 @@ export interface DiffItem {
 
 export interface WorkflowVersionRequest {
   definition: string // workflowDefinition
+  references?: Reference[] // List of API references attached to the
+                           // workflow (source descriptions in Arazzo
+                           // vocabulary)
 }
 
 export interface WorkflowVersionResponse {
modified   src/core/workflow-deploy.ts
@@ -50,9 +50,9 @@ export class WorkflowDeploy {
   ): Promise<WorkflowVersionResponse | undefined> {
     let version: WorkflowVersionResponse | undefined
 
-    const request: WorkflowVersionRequest = {
-      definition: workflowDefinition.rawDefinition,
-    }
+    const [definition, references] = await workflowDefinition.extractDefinition()
+
+    const request: WorkflowVersionRequest = {definition, references}
 
     // eslint-disable-next-line prefer-const
     version = await this.createWorkflowVersion(mcpServer, request, token)

[fbraure]

LGTM