fix: break and indent assignments like declarations

[jtkiesel]

What changed with this PR:

Assignment expressions with boolean expression righthand sides no longer break/indent poorly, and assignment expressions in general are now printed the same way as variable declarations.

Example

Input

class Example {

  void example() {
    double availability12 =
      (double) successfulCount / (successfulCount + failureCount);
    availability12 = (double) successfulCount /
    (successfulCount + failureCount);

    var lineLengthInAssignmentMoreThanPrintWidth =
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890";
    lineLengthInAssignmentMoreThanPrintWidth = "1234567890" +
    "1234567890" +
    "1234567890" +
    "1234567890" +
    "1234567890" +
    "1234567890";

    aaaaaaaaaa +=
    bbbbbbbbbbb +
    ccccccccccc +
    ddddddddddd +
    eeeeeeeeee +
    ffffffffff +
    gggggggggg;
    aaaaaaaaaa %=
    bbbbbbbbbbb +
    ccccccccccc +
    ddddddddddd +
    eeeeeeeeee +
    ffffffffff +
    gggggggggg;
    aaaaaaaaaa <<=
    bbbbbbbbbbb +
    ccccccccccc +
    ddddddddddd +
    eeeeeeeeee +
    ffffffffff +
    gggggggggg;
    aaaaaaaaaa &=
    bbbbbbbbbbb +
    ccccccccccc +
    ddddddddddd +
    eeeeeeeeee +
    ffffffffff +
    gggggggggg;

    var something =
      MyClass.staticFunction(
        aaaaaaaaaa,
        bbbbbbbbbbb,
        ccccccccccc,
        ddddddddddd
      ) +
      0;
    something = MyClass.staticFunction(
      aaaaaaaaaa,
      bbbbbbbbbbb,
      ccccccccccc,
      ddddddddddd
    ) +
    0;
  }
}

Output

class Example {

  void example() {
    double availability12 =
      (double) successfulCount / (successfulCount + failureCount);
    availability12 =
      (double) successfulCount / (successfulCount + failureCount);

    var lineLengthInAssignmentMoreThanPrintWidth =
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890";
    lineLengthInAssignmentMoreThanPrintWidth =
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890" +
      "1234567890";

    aaaaaaaaaa +=
      bbbbbbbbbbb +
      ccccccccccc +
      ddddddddddd +
      eeeeeeeeee +
      ffffffffff +
      gggggggggg;
    aaaaaaaaaa %=
      bbbbbbbbbbb +
      ccccccccccc +
      ddddddddddd +
      eeeeeeeeee +
      ffffffffff +
      gggggggggg;
    aaaaaaaaaa <<=
      bbbbbbbbbbb +
      ccccccccccc +
      ddddddddddd +
      eeeeeeeeee +
      ffffffffff +
      gggggggggg;
    aaaaaaaaaa &=
      bbbbbbbbbbb +
      ccccccccccc +
      ddddddddddd +
      eeeeeeeeee +
      ffffffffff +
      gggggggggg;

    var something =
      MyClass.staticFunction(
        aaaaaaaaaa,
        bbbbbbbbbbb,
        ccccccccccc,
        ddddddddddd
      ) +
      0;
    something =
      MyClass.staticFunction(
        aaaaaaaaaa,
        bbbbbbbbbbb,
        ccccccccccc,
        ddddddddddd
      ) +
      0;
  }
}

Relative issues or prs:

Closes #687