Change the Error to Exception to conform with the sonar standards

GCP-10161

Reviewer: Daniel Jao
Migrate static strings to internationalization files.

GCP-10161

Reviewer: Daniel Jao
Refactor the validation of item to delete in GermplasmListTreeUtil (similar to the BreedingManager approach)

GCP-10161

Reviewer: Daniel Jao
Created test class for validation of item deletion for GermplasmListTreeUtil

GCP-10161

Reviewer: Daniel Jao
Apply the common method for current local user retrieval in GermplasmStudyBrowser

GCP-10161

Reviewer: Daniel Jao