Support multiple entries of source + list_to_map_when condition in list-to-map processor

[niketan16]

Is your feature request related to a problem? Please describe.
Allow the list-to-map processor to convert multiple sources (a list of objects from an event) to maps of keys to objects under different conditions.

Describe the solution you'd like
Modify list-to-map processor to support this new configuration that allows multiple entries of source and list_to_map_when conditions like shown below. The existing configuration is still supported. This is new config under entries needs to be added.

processor:
    - list_to_map:
        entries:
           - source: "mylist"
             key: "name"
             value_key: "value"
             flatten: true
             list_to_map_when: "some-key == 'test'"
           - source: "mylist2"
             key: "name2"
             value_key: "value2"
             flatten: true
             list_to_map_when: "some-key2 == 'test2'"

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Additional context
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