🩹 [Patch]: Add module configuration setting for rich UI rendering

[MariusStorhaug]

Describe the change

Overview

Add a configuration setting to control rich UI rendering. This setting should determine how output is rendered by default, based on the environment's support for virtual terminal features.

Details

• Introduce a new module configuration setting (e.g., RichUIRendering) that determines whether rich UI rendering is enabled.
• The default value should depend on $Host.UI.SupportsVirtualTerminal. If supported, set $PSStyle.OutputRendering = 'Ansi'; otherwise, set it to 'Host'.
• Replace all direct usages of $Host.UI.SupportsVirtualTerminal throughout the codebase with (Get-GitHubConfig -Name <new setting>) so that UI rendering can be fully controlled via config.
• This makes it possible to override the automatic detection for testing or custom scenarios.
• Requirement: Whenever Set-GitHubConfig -Name 'RichUIRendering' -Value $true or $false is called, the function MUST set $PSStyle.OutputRendering to 'Ansi' or 'Host' respectively, immediately after updating the config value.

Acceptance Criteria

• New config setting exists and defaults are properly set
• All usages of $Host.UI.SupportsVirtualTerminal updated to use config
• Whenever Set-GitHubConfig -Name 'RichUIRendering' -Value ... is called, $PSStyle.OutputRendering is updated accordingly
• Documentation updated to reflect new configuration
• Backwards compatibility maintained for environments without virtual terminal support

Example

In Set-GitHubConfig function

if ($Name -eq 'RichUIRendering') {
    if ($Value -eq $true) {
        $PSStyle.OutputRendering = 'Ansi'
    } else {
        $PSStyle.OutputRendering = 'Host'
    }
}

In the private variable that sets the default config:

RichUIRendering = $Host.UI.SupportsVirtualTerminal

This implementation provides flexible and testable UI rendering configuration for the module.