IDP Preset overwritten on Lambda Save

[Wawrzyn321]

Description

Changes proposed in this pull request:

• Fix core configuration (nonexistent property was used)
• Fix lambda edit mode (issuer was not assigned on load)

Testing scenario:
0. On dev, apply changes made in core/src/app/app.config.ts (use gateway_kyma_project_io_version). It will enable you to display lambda details in APIs view, otherwise request will 404.

1. Create custom IDP preset.
2. Create lambda, choosing HTTP Trigger and your custom identity provider.
3. Go to APIs and select your new lambda. It should display your IDP properly.
4. Get back to lambda details and refresh the page, then just hit 'Save' button.
5. If you check out the lambda on APIs again, then without a fix "issuer" field will be brought back to default.

Related issue(s)
Console