kcms/runners: Rename to "Plasma Search" and clarify scope of options
In the past this KCM was called "Plasma Search", but we renamed it to "KRunner" because its options only applied to KRunner (and technically the Milou plasmoid but we forgot about that).
Then we made Kickoff use the same plugins as KRunner. Then we added the Overview effect which also has a KRunner-powered search that uses the same plugins.
So it's time to return the KCM to its former name "Plasma Search" since this is now more accurate. One slight complication is that since then the KCM gained a few options that are in fact specific only to KRunner, so they are slightly renamed to indicate this.
In the future it might be better to move these into a KRunner-specific config window like we have for Plasma applets.
KCM now:
