Add ignore_invalid_paths to patch

[tulinmola]

Sometimes it's necessary to apply a patch to a JSON that may lack certain operation paths. In this scenario, it would be great to have an option to ignore the invalid paths. I provide the following example:

      iex> # Patch will succeed, not applying invalid path operations.
      iex> patch = [
      ...> %{op: "replace", path: "/name", value: "Alice"},
      ...> %{op: "replace", path: "/age", value: 42}
      ...> ]
      iex> target = %{"name" => "Bob"} # No age in target
      iex> Jsonpatch.apply_patch(patch, target, ignore_invalid_paths: true)
      {:ok, %{"name" => "Alice"}}

Thanks for this great library. Simple and useful!
Tulo

[corka149]

Hi Tulo. Thanks four your PR! It looks good to me. Could you fix the Credo issue? Then I can merge.

[corka149]

As credo reported:

Function body is nested too deep (max depth is 2, was 3).

[corka149]

One option would be to extract the whole block as own function to avoid deep nesting.