Improve Display Impl - Each ValidationError should be on its own line

[aarashy]

The current impl for Display doesn't break newlines frequently enough.

The display output of the list variant of ValidationErrorsKind currently looks like the following:

my_field[0].subfield: Validation error: Some error. [{"value": String("some-value")}]my_field[1].subfield: Validation error: Some error. [{"value": String("some-value-2")}]
other_field[0].other: Validation error: Other error [{"value": String("other-value")}]

It only breaks line when the top-level field of the ValidationErrors changes. I would prefer for it to look like the following:

my_field[0].subfield: Validation error: Some error. [{"value": String("some-value")}]
my_field[1].subfield: Validation error: Some error. [{"value": String("some-value-2")}]

other_field[0].other: Validation error: Other error [{"value": String("other-value")}]

It seems pretty clear that separate field-level errors belong on their own line - having multiple on the same line always looks bad. Having multiple line-breaks when the top-level field changes doesn't feel like a regression either, but we could remove the existing writeln! call if we wanted a maximum of 1 new line after every error display.

[aarashy]

Hi, thanks for the approval - the issue with CI seems unrelated to this PR, right?

[Keats]

It seems unrelated yes

[aarashy]

Would you like me to re-run the CI or will you merge this later?

[Keats]

That's fine to leave like this, I'll merge for the next release

[dslemusp]

is this going to be merged?

[Keats]

The concept probably, but ideally there will be an error rewrite for the next version to make it simpler.