Make Map.of() and ImmutableMap.of() more readable

Currently, the formatter will format Map.of() as either:

// Shorter list
Map<String, String> map1 = Map.of("key1", value1, "key2", value2, "key3", value3);

// Longer list
Map<String, String> map2 = Map.of(
        "key1",
        longerValue1,
        "key2",
        longerValue2,
        "key3",
        longerValue3,
        "key4",
        longerValue4,
        "key5",
        longerValue5,
        "key6",
        longerValue6);

These are not very readable, especially when the keys are not visually distinguishable from values.

It would be much more readable if it would format them like this instead:

// Shorter list
Map<String, String> map1 = Map.of(
        "key1", value1,
        "key2", value2,
        "key3", value3);

// Longer list
Map<String, String> map2 = Map.of(
        "key1", longerValue1,
        "key2", longerValue2,
        "key3", longerValue3,
        "key4", longerValue4,
        "key5", longerValue5,
        "key6", longerValue6);

You may need to special case Map.of() and ImmutableMap.of(), as I don't think there is any more general rule.

Start by locating the formatter logic that handles Map.of() and ImmutableMap.of(); no source files or tests are named in the issue. Add regression coverage for the shorter and longer examples, then verify that each key-value pair is kept together on its own line while existing formatting remains unchanged.