feat(containers-plugin): Being able to add custom containers

[brenoepics]

Is your feature request related to a problem? Please describe.

Currently, you can change the label but you cannot add new containers for new colors and/or icons.
Containers Plugin

Describe the solution you'd like

Adding custom containers to ContainerOptions, then users could add it in DefineConfig / DefineConfigWithTheme

//containers.ts
export interface ContainerOptions {
  infoLabel?: string
  noteLabel?: string
  tipLabel?: string
  warningLabel?: string
  dangerLabel?: string
  detailsLabel?: string
  importantLabel?: string
  cautionLabel?: string
  customContainers?: ...
}

// config.ts
export default defineConfig({
  // ...
  markdown: {
    container: {
      tipLabel: '...',
      warningLabel: '...',
      dangerLabel: '...',
      infoLabel: '...',
      detailsLabel: '...',
      customContainers: [ ... ]
    }
  }
  // ...
})

Describe alternatives you've considered

Disabling GitHub Flavored Markdown-It plugin and registering again with custom alerts.

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the docs.
• Read the Contributing Guidelines.
• Check that there isn't already an issue that asks for the same feature to avoid creating a duplicate.

[dragomano]

I'd also like to be able to translate all these containers on sites with multiple languages.

[comfuture]

I strongly agree with this opinion.
It would be very flexible if a container plugin were provided or allowed users to create one, reusing features like displaying items already implemented in the Home layout.

For example:

::: flex-container{cols=3}
...
:::

Although the goal is somewhat different, being able to extend components in a form similar to https://nuxt.com/modules/mdc would be extremely convenient.