QNTM-5867 Search dictionary should only be recreated when necessary

[scottmitchell]

Purpose

This PR addresses jira task QNTM-5867: Search dictionary should only be recreated when necessary. It creates a TagDictionary property that is cached and only recreated when necessary. The tag dictionary used to be a local variable that was recreated with every single search.

This PR does:

• Cache the tag dictionary and only recreates it when necessary
• Roughly doubles the speed of the Search() method in SearchDictionary

master	QNTM-5867
56.6	8.2	Average Search() time in ms
7.5	4	Median Search() time in ms

This PR does NOT:

• Impact Dynamo instrumentation

Declarations

Check these if you believe they are true

• The code base is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning, and are documented in the API Changes document.

Reviewers

@ColinDayOrg @mjkkirschner

FYIs

[ColinDayOrg]

LGTM

[mjkkirschner]

LGTM