MET Trigger: Migrate flags

Migrate flags from base class of non-MT tools (EFMissingETBaseTool) to base class of MT tools (IMissingETTool).

Part of MET Trigger clean up series (ATR-19488).

This merge request affects 1 package:

• Trigger/TrigAlgorithms/TrigEFMissingET

Adding @rewang ,@ggallard ,@mronzani as watchers

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

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-21854-2019-03-12-21-19
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST 35300]

added review-user-action-required label and removed review-pending-level-1 label

mentioned in merge request !21852 (merged)

added review-pending-level-1 label

removed review-user-action-required label

resolved all discussions

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

mentioned in commit 88eb288e

merged

added sweep:ignore label