Optimize the Save function

[amiremohamadi]

DuckX is using zip library that only supports appending or writing new files. (unable to update a file inplace!)
So currently Save function works as follows:

• make a new file
• write any new files
• copy the old files
• delete old docx
• rename new file to old file

And this process has a terrible performance on large files!

[CihanSari]

Maybe use zlib and make use of this example / demo: https://github.com/skeeto/zlib-mutate-demo?

[amiremohamadi]

Maybe use zlib and make use of this example / demo: https://github.com/skeeto/zlib-mutate-demo?

zlib is an awesome library and has great features. But as you may know I want to keep duckx as minimal as possible and zlib has a large codebase. So If there was no solution, we might switch to zlib or a similar library in the future.