feat(stepfunctions): Multiple Workflow Studio integration improvements and fixes

[witness-me]

Multiple Workflow Studio integration improvements and fixes:

Problem

1. Currently the indentation setting used in the integration defaults to 4 spaces. If it's different in user's VSCode setting, the spacing for the string sent from the integration will not match
2. Currently context menu lacks the command to launch WFS. It has been added before, but it looks it was accidentally added to auto-generated file and was thus removed later
3. WFS editor is opened by default in all modes, including conflict resolution and some other views
4. Bug: when opening split panel while having WFS integration open, it opens a panel with custom editor, which stays empty since we already have an instance of WFS editor launched for that file
5. Bug: If the webview is unavailable (e.g. CDN is down or the user is offline), integration throws an error modal and the file can't be opened easily, even in the default editor
6. Bug: when YAML in the local file is invalid, WFS integration is opened to the file, but since it fails to transform YAML to valid JSON, it opens with empty definition

Solution

1. Passing a user setting for tab spacing to be used on the webview side to format JSON/YAML with the right indentation
2. Adding an option to launch WFS from context menu, as it was added before (but this time in the right package.json)
3. Add editorAssociation to not open WFS in specific environments that do not require it
4. When opening split panel panel while having WFS integration open, open that file in default editor
5. If the webview is unavailable, open file in default editor
6. When YAML in the local file is invalid, open default editor instead of WFS and show warning message (similar to what we do for invalid JSON)

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