szip: zip_files() and zip_folder() should have options to change the used compression level

[rhoellwarth]

Describe the feature

The two functions zip_files and zip_folder should have an option to control the level of compression. Right now in both functions the compression level is hard coded with ".no_compression.

Use Case

The two functions now work like "tar" - they just create a single file that's not compressed. But when I read "zip" I always expect that the resultfile is compressed. Now I have to fiddle around with the details of szip instead of just using it.

Proposed Solution

For zip_folder I tried the following two changes - and they seamed to work. For zip_files there must be done some more work but it should be very likely:

--- a/vlib/szip/szip.v
+++ b/vlib/szip/szip.v
@@ -8,6 +8,7 @@ import os
 [params]
 pub struct ZipFolderOptions {
        omit_empty_folders bool
+       compression_level  CompressionLevel = .no_compression
 }

 struct C.zip_t {
@@ -273,7 +274,7 @@ pub fn zip_folder(folder string, zip_file string, opt ZipFolderOptions) ! {
        })

        // open or create new zip
-       mut zip := open(zip_file, .no_compression, .write)!
+       mut zip := open(zip_file, opt.compression_level, .write)!
        // close zip
        defer {
                zip.close()
```

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### Version used

V full version: V 0.3.3 a6bf20f.9794a23

### Environment details (OS name and version, etc.)

I did a "v up" before creating this issue.

V full version: V 0.3.3 a6bf20f.9794a23

[JalonSolov]

PRs are always welcome! However, I would change

        compression_level  CompressionLevel = .no_compression

to the actual Zip default (6, isn't it? Whatever enum that corresponds to...).