StringUtils: Trimming leading and trailing white-spaces when chomping "all"

[AlexanderInova]

Fixes an issue which produces invalid formatting of emphasis and strong emphasis when the HTML element contains leading or trailing white-spaces, which is not allowed within markdown (see https://spec.commonmark.org/0.31.2/#example-351).

Related to #388

[mysticmind]

@AlexanderInova There is a tricky use case i.e. html text example html <i>code </i>block as per our unit test, this is failing. What do you expect as the markdown for this case? example html *code *block or example html *code* block?

There is more to this as a fix, looking into it.

[AlexanderInova]

@mysticmind Yes, I had a feeling that just simply extending this method would solve all issues. :)

What do you expect as the markdown for this case? example html *code *block or example html code block?

The basic expectation should be: "valid mark-down". Your second example looks fine to me.

There is more to this a a fix, looking into it.

Thank you very much. I will try to get deeper into this at monday.

[mysticmind]

I have got a neat fix which solves the issue for all emphasizes, will push the change do a release. I am closing this PR.

[mysticmind]

@AlexanderInova I have added fixes and released 4.4.0. Please check.

[AlexanderInova]

@mysticmind We updated to 4.4.0 and it looks very good now. Our quality assurance will have a deeper look on the results monday. I will give you the final feedback within the original issue (#388).

Thank you very much.
We very much appreciate your help, as well as your whole work on this library. ❤️