Make shorthand optional in new flag constructor functions

## Problem
Currently, the new flag constructor functions require the shorthand parameter to be set, which can limit flexibility and usability when a shorthand is not desired or needed.

## Proposal
Update the new flag constructor functions to allow the shorthand parameter to be optional, so it can be omitted when not required.

## Expected Benefits
- Improves ergonomics for API consumers who don't want to specify a shorthand.
- Aligns with typical flag constructor conventions.

## Acceptance Criteria
- The shorthand parameter in new flag constructor functions is optional.
- Backwards compatibility is maintained.
- Unit tests are added/updated for cases with and without shorthand.

Locate the new flag constructor functions and their unit tests, then read how shorthand is currently required. Add coverage for constructors with and without shorthand, preserving existing calling behavior. Done means shorthand can be omitted, existing uses remain compatible, and the unit tests pass.

Written by the indexing model from the issue text.