Add an option to parse string versions into FixedFileInfo

[yalegko]

During our release pipeline we always need to update all version components of the versioninfo.json, which is a bit tedious as we not only have to update version strings, but also split the strings an a number components to fill the FixedFileInfo structs

We used to use a small utility to parse and insert new version in to the JSON file, but it seems as a common problem for most of goversioninfo users (at least for those, who want to add a version into the binary)

Here we propose a new CLI option which will use "string versions" set in StringFileInfo (or using --file-version and --product-version flags) to fill the corresponding structs in the FixedFileInfo