Update conditionalAssignment rule to support more complex lvalues

[calda]

This PR updates the conditionalAssignment rule to support more complex lvalues. Previously it required that the value being assigned was just a simple identifier like foo =. Now it supports more complex lvalues like foo?.bar =, foo["bar"] =, etc.

For example, this sample code was left as-is before:

switch condition {
case true:
    property?.foo!.bar["baaz"] = Foo("foo")
case false:
    property?.foo!.bar["baaz"] = Foo("bar")
}

Now it is updated as expected:

property?.foo!.bar["baaz"] =
    switch condition {
    case true:
        Foo("foo")
    case false:
        Foo("bar")
    }

I also added a new --condassignment after-property to let consumers disable the new functionality added in #1643. After running the updated rule on our codebase, I found too many of the changes weird and unusual. On the other hand I found the previous behavior (only applying the new syntax after a new property declaration) reasonable almost all of the time.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.16%. Comparing base (9ce956c) to head (a11c38d).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1647      +/-   ##
===========================================
- Coverage    95.18%   95.16%   -0.03%     
===========================================
  Files           20       20              
  Lines        22498    22522      +24     
===========================================
+ Hits         21414    21432      +18     
- Misses        1084     1090       +6     

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