Checkmk Werk 14987: Extension packages: Enforce semantic versioning

ID: 14987 Title: Extension packages: Enforce semantic versioning Component: Checks & agents Level: 1 Class: New feature Version: 2.2.0i1 This Werk only affects maintainers of Checkmk <i>Extension Packages (MKP)</i>. We now enforce both in the GUI and on the commandline the use of <a href="https://semver.org">semantic versioning</a>. Previously the GUI only allowed strings consisting of dots and digits (such as <tt>"..7"</tt>). The commandline on the other hand would allow any string at all (such as <tt>"🐟semmel"</tt>). We meet in the reasonable middle, and enforce values resembling semantic versioning upon creation or modification of packages. For now, packages with any other version string will continue to work. The <a href="https://exchange.checkmk.com/">Checkmk Exchange</a> no longer accepts packages with other versioning. <b>Note:</b> Some backend operations require us to sort the packages (to install the newest). We try our best to compare all version strings as reasonable as possible, but there are limitations. For instance: <tt>v10</tt> will be considered older than <tt>v2</tt> (because the "v" prevents an interpretation as number). This change allows to implement a well-defined version comparison in the future, allowing us to move forward with features and streamlined workflows.