fix(issue): fix using issue commands from non-git dir

Description

Allow using issue commands from a directory without git initialized.

Here is more detailed explanation on why this is happening #1423 (comment 1502644171)

Related Issues

Resolves #1423 (closed)

How has this been tested?

From any directory with no git initialized in it, run glab issue subscribe <ISSUE_URL>. That also affects several other issue subcommands, such as: unsubscribe, close, reopen, and delete.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)
• Test gap

Closes #1423 (closed)