fix: proper indenting of snippet within an array

[rickcowan]

What does this PR do?

When choosing a snippet to auto-complete within an array, the indentation level was wrong on the lines below the insertion point.

example:
  - #cursor here

would auto-complete to:

example:
  - item1: "some item"
  item2: "another item"

rather than:

example:
  - item1: "some item"
    item2: "another item"

What issues does this PR fix or reference?

no ref

Is it tested? How?

Manual tests as well as new unit test.

[coveralls]

Coverage increased (+0.003%) to 82.557% when pulling 422beb0 on jigx-com:fix/code-snippet-in-array into cd71414 on redhat-developer:main.

[msivasubramaniaan]

LGTM

[gorkem]

Approved. There is a typo on the commit message "identing" instead of "indenting". You can optionally fix that.