StoreGate: use std::string for key type in HandleKey

Replace the class K template parameter in all auto-declaring HandleKey property constructors with plain std::string. We don't ever use anything else as SG key and this resolves ambiguities in case other constructor types are defined (see !58618 (merged) for discussion).

Build area was cleaned as per request posted in the DB. The full software build will be performed

This merge request affects 1 package:

• Control/StoreGate

This merge request affects 10 files:

• Control/StoreGate/StoreGate/ReadCondHandleKey.h
• Control/StoreGate/StoreGate/ReadHandleKey.h
• Control/StoreGate/StoreGate/ReadHandleKey.icc
• Control/StoreGate/StoreGate/ReadMetaHandleKey.h
• Control/StoreGate/StoreGate/ThinningHandleKey.h
• Control/StoreGate/StoreGate/ThinningHandleKey.icc
• Control/StoreGate/StoreGate/TypelessWriteHandleKey.h
• Control/StoreGate/StoreGate/WriteCondHandleKey.h
• Control/StoreGate/StoreGate/WriteHandleKey.h
• Control/StoreGate/StoreGate/WriteHandleKey.icc

Adding @ssnyder as watcher

added Core JetEtmiss master review-pending-level-1 labels

CI Result SUCCESS (hash b9db24bb)

	Athena	AthSimulation	AthGeneration	AthAnalysis
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AthAnalysis: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 62745]

lgtm approving -- L1

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 1b64cd57

added sweep:ignore label