[FEATURE] Create target index with specific settings while rollup

[MrChaos1993]

Is your feature request related to a problem?
It is not possible to setup settings for index created while rollup.

What solution would you like?
If during the execution of rollup job index will be created, it will be created with settings passed by user into job settings as follows:

...
    "target_index": "rollup-test-index",
    "target_index_settings": {
      "index.codec": "zlib"
    },
...

target_index_settings can be null. In this case behaviour will be same as before.

What alternatives have you considered?
Only one alternative way is to create index before rollup.