Fix for BigStringCustomEditor not being able to save Strings backed by byte arrays

[SirIntellegence]

I have also simplified some logic related to accessing the backing data. My light tests (of opening and debugging a Java app) passed.

[SirIntellegence]

Right, issue link: #6147

[matthiasblaesing]

Thank you for working on this. I recently ran into this problem and wanted to have a look.

If I understand it correctly you apply the same fix you did for the "view" implementation also to the "save" implementation and factor out the common code.

The approach looks ok to me and works. However, I think the wording and organisation could be improved. I left a few inline comments, please have a look. Thank you.

[matthiasblaesing]

Thank you. I was able to verify, that his worked for Latin1 and UT-16 compact strings.

I'm down to stylistic comment (see inline), which is a good sidn. Basicly please add a bit of whitespace around the methods.

When this is done, please squash the commits into a single one, I'm willing to merge.

[SirIntellegence]

One more possible quick check before squash? Or should I just squash?

[matthiasblaesing]

@SirIntellegence sorry, got message to late. Looks sane to me now. Please squash and I'll merge.

[mbien]

going to squash and force push into this PR later unless someone is faster, since the deadline is today night UTC - would be a shame to miss out on it.

[matthiasblaesing]

@mbien thanks for stepping in. PRs are green. I checked, that the squash did not change the modfied file. Lets merge.

[matthiasblaesing]

Oh and of course @SirIntellegence thank you for caring enough to fix the issue ;-)

[SirIntellegence]

Ah, right. Sorry. I got to squish XD. Thanks.