XML editor - option to show all code of the ETL process

Currently the XML editor is limited in functionality:

1. Find and replace is missing (there is a separate idea for this: JS-I-1557)

2. The XML editor can only show the currently selected ETL element, e.g. job, transform

Solution: Have a drop-down in the XML editor button to include all previous ETL elements.

Use case: Find and replace certain columns/variables in many different ETL processes at once.

Example: Clicking on Field Transform, which has a tablue union below and that table union consists of two extracts

Selecting new feature XML editor "show all" results in:

</transform>

<transform name="..." type="FieldTransform" ...>

...content...

</transform>

<transform name="..." type="TableUnion" ...>

...content...

</transform>

<extract X>

...content...

</extract>

<extract Y>

...content...

</extract>