Add prefix option

[lexuzieel]

This PR includes fixes and changes from feat-titlecase branch and closes #80

[MichaelCurrin]

Some refactor and cleanup changes please

[MichaelCurrin]

Did you make the main function just to use async?

In newer Node you can use async/await without a function.

[lexuzieel]

In my editor and when trying to run the test I receive the following error (running with node 16.14.2):

src/test/runTest.ts:25:3 - error TS1378: Top-level 'await' expressions are only allowed when the 'module' option is set to 'es2022', 'esnext', 'system', 'node16', or 'nodenext', and the 'target' option is set to 'es2017' or higher.

[MichaelCurrin]

Hi, I am still going to look at this. I need to revert some of the commits in this before I can bring it in and I have been sorting out bug issues lately on the repo instead.

[lexuzieel]

Hello. Sorry for my inactivity on this PR. I have read your comments, however I currently have no time to implement them.
Also you were right. After using this extension with my changes for some time it appears it does not capitalize properly in some cases (sometimes it broke after the first conversion). So it looks like it will need more work.

[lexuzieel]

Hello 👋
I've merged upstream master branch with feat-prefix of my fork and corrected all but one issues with the code style (see the comment).
I guess now we somehow merge your PR with this one since it is related to a single feature and cover it with more test cases?