Import command option to not upgrade installed packages

[jpawlowski]

Description of the new feature / enhancement

winget import currently will also install newer versions of packages that are already installed.

There shall be the option to ignore packages that are already installed on the system, no matter the version. This will safe a lot of time when one just wants to install any missing software and not mix this up with upgrades.

Proposed technical implementation details

Implement a command line option --ignore-installed to skip re-installing(=upgrading) a package.

[jedieaston]

Related: #929

[Trenly]

@denelon - #2655

[denelon]

@Trenly did this make it into 1.4 Release Candidate (2)?

[Trenly]

@Trenly did this make it into 1.4 Release Candidate (2)?

Looks like it did