Attaching numbering to custom style

[anti-the-social]

Issue: #1147
Here are my first deep touches on docx :) Interesting structure, I should admit, took some time to learn it.

To sum PR up:

1. Moved numbering props level higher at src/file/paragraph/properties.ts
   from IParagraphPropertiesOptions to IParagraphStylePropertiesOptions
2. Added numId replacer at src/export/packer/next-compiler.ts for styles.xml
3. Added demo on how it meant to be used at demo/11-declaritive-styles-2.ts

Didn't came up with some good tests since numbering is covered, while NumberingReplacer isn't in general.

[dolanmiu]

Looks good!

@anti-the-social quick question, I can see the numbering part of the interface has been shifted to another location

Will this affect other areas of docx? Breaking change?

[anti-the-social]

@dolanmiu it sort of expands the library, not narrows so it shouldn't break anything.
But there is a chance that IParagraphStylePropertiesOptions(where I moved numbering) used in the places where numbering things are not allowed by Word.
Have not checked that yet. I'll try to check that once have time