Fix issue with GetOptions resetting variable and account for KeepPkgCache

[lrandersson]

Description

This PR introduces an issue detected with NSIS GetOptions resetting the value of ARGV_NoRegistry as well as properly accounted for the CLI arg KeepPkgCache, looks like this was ignored before.

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[marcoesters]

Suggested change

	* EXE: Fixed an issue for silent installers where command-line argument `/KeepPkgCache` was ignored and `/NoRegistry` would reset the default value.
	* EXE: Fixed an issue for silent installers where command-line argument `/KeepPkgCache` was ignored and `/NoRegistry` would reset the default value. (#1132)

[lrandersson]

19e254d

[marcoesters]

This seems brittle. Instead of manually parsing the construct.yaml file, I suggest using the UninstallString value and see if it starts with $INSTDIR\Uninstall-:

constructor/constructor/nsis/main.nsi.tmpl

Lines 1627 to 1628 in 7a837bd

	WriteRegStr SHCTX "${UNINSTREG}" "UninstallString" \
	"$\"$INSTDIR\Uninstall-${NAME}.exe$\""

[lrandersson]

Hmm, what about using the variable installer we get from create_installer? If I'm not mistaken that should be the path to the exe and it is named as <name>-<version>-<build number>-<platform>-<arch>.exe. If we split installer.name on - we have name from [0] and version from [1], let me know what you think.

[marcoesters]

I don't think the installer uses the build number (it's part of the version string), but that could work, too.

[lrandersson]

Reduced it to

    installer_file_name_parts = Path(installer).name.split("-")
    name = installer_file_name_parts[0]
    version = installer_file_name_parts[1]
    partial_name = f"{name} {version}"