Fix inconsistencies in naming of `notification-configuration`

The `notification-configurator` has multiple synonyms:

| Name | Meaning |
|-|-|
| `notification-configuration` | Name of [the directory, the namespace and VS solution file](https://github.com/Azure/azure-sdk-tools/tree/main/tools/notification-configuration), which builds the [`notification-creator` tool executable](https://github.com/Azure/azure-sdk-tools/blob/main/tools/notification-configuration/notification-creator/Azure.Sdk.Tools.NotificationConfiguration.csproj#L7). |
| `notification-creator` | See above. |
| `NotificationConfigurator` | Name of the class having the core logic of `notification-creator`, which is called from `Program.Main()`, [here](https://github.com/Azure/azure-sdk-tools/blob/main/tools/notification-configuration/notification-creator/Program.cs#L63). |
| `notification-generation` | Name used in [the pipeline that runs `notification-creator` on the daily basis](https://dev.azure.com/azure-sdk/internal/_apps/hub/ms.vss-build-web.ci-designer-hub?pipelineId=679&nonce=i5KvPD49er1FV6LuB1LDxA%3D%3D&branch=main). |

The goal of this work is to make the naming uniform.

For example: the `ado-notification-creator` solution would live in `ado-notification-creator` directory. It would build `ado-notification-creator` tool, whose core logic would be in `AdoNotificationCreator.AdoNotification` class (or similar). The pipeline running it would be called `create-ado-notifications`.

Once this is done, following doc needs to be updated:

https://dev.azure.com/azure-sdk/internal/_wiki/wikis/internal.wiki/63/Subscribe-to-Notifications?anchor=pipelines-and-sources