Implement apply_if action property

[a-ast]

Actions will be more powerful if we add additional condition

actions:
    -
        type: set
        field: name
        locale: en_GB
        scope: null
        expression: 'trim(value("name", null, "en_GB"))'
        apply_if: 'hasValue("name", null, "en_GB"))'

apply_if is an expression.
Action is applied only if apply_if is evaluated as true.