Change display of zero frequency from - to 0 in quick

Description

Closes issues: Related issues:

When a variant is annotated with 0 frequency in all sources, the HI FREQ and HI COUNT columns in QUICK view would display a -.

Change it to actually display 0 making it easier to distinguish from the case where no sources has annotated the variant.

Notes to reviewer

Type of change

Application (affects UI or general functionality):

• New feature
• Bug fix
• Improvement

Ops / admin / CI related only (not impacting users):

• New feature
• Bug fix
• Improvement

Tests

General

• Tests have been added that prove my fix is effective or that my feature works
• Related tests have been modified/removed

Hypothesis testing:

• Soak testing has been done
• Distribution between positive / negative cases has been checked

Database

• Includes changes to database schema
• Includes necessary database migrations

Configuration

• Includes changes to configuration
• Includes configuration migration instructions in documentation

Merge checklist

• Self-review of code performed
• Feature review against specification (if applicable)
• Need for documentation has been evaluated and, if necessary, updated
• Code and implementation is reviewed by other core developer (all changes, inc. changes based on initial review)