[Windows] Consider using 7z for installer archives

[mcdurdin]

In testing, using 7-Zip instead of Zip reduced the Keyman Developer 10 installer archive from 84MB to 56MB.

There are a number of ways we could embed the 7-Zip library to decompress:

1. Include 7z.dll as a resource in setup.exe, and automatically extract and use it if a .7z file is found in the appended archive.
2. Create a SFX and embed that in the installer, calling it silently to extract when setup starts.
3. Use native Delphi LZMA code; however this is quite slow.

[mcdurdin]

Note: using msi compression=high reduced installer from 84MB to 70MB. We can still get an additional 14MB (less 7Z library size) by using 7Z but may look at this for KM12 instead when we embed CEF in Keyman Desktop, where installer size is more significant.

[mcdurdin]

Suggested yesterday: xz. Looks more maintained than 7z at this time.

https://github.com/delphiunderground/xz-examples-delphi
https://tukaani.org/xz/

[mcdurdin]

This is a fair bit of work and seems to be low priority as download size is not considered a serious issue by any of our testing community.