Add Rename-PodeOADefinitionTag Function

[mdaneri]

Description of the Change:
This pull request introduces a new function, Rename-PodeOADefinitionTagName, which allows renaming an existing OpenAPI definition tag in Pode. This enhancement simplifies the management of OpenAPI definition tags and ensures a more streamlined configuration process.

Key Changes:

• Added Rename-PodeOADefinitionTagName function.
• The function renames a specified Definition Tag or the default tag if no tag is specified.
• Ensures that the new tag name does not already exist.
• Updates the default and selected definition tags if applicable.
• Throws an error if used within a Select-PodeOADefinition script block.
• Includes improvements to the way the default OpenAPI definition tag is managed.

Examples:
Renaming a specific OpenAPI definition tag:

Rename-PodeOADefinitionTag -Tag 'v.3' -NewTag 'v.3.0.3'

Renaming the default OpenAPI definition tag:

Rename-PodeOADefinitionTag -NewTag 'NewDefault'

Notes:

• The function will throw an error if the new tag name already exists.
• The function cannot be used inside a Select-PodeOADefinition script block.

Pester Tests:
Included Pester tests to validate the functionality:

• Renaming a specific OpenAPI definition tag.
• Renaming the default OpenAPI definition tag.
• Handling errors when the new tag name already exists.
• Handling errors when used inside a Select-PodeOADefinition script block.

Documentation:
For detailed usage and examples, refer to the documentation file included in the pull request.