Allow customizing the namespace separator for autocompletion

[Jangyusu]

Is your feature related to a specific framework or general for this extension

General

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

The autocompletion feature currently suggests key paths using a dot (.) as a separator (e.g., namespace.key). My project, however, uses a colon (:) as a separator (e.g., namespace:key). Because of this, the autocompletion suggestions do not match our key format, which forces us to manually correct the separator every time we use a suggestion.

Describe the solution you'd like

I would like a new configuration option in the settings where I can customize the key path separator for autocompletion.

For example, a setting like i18n-ally.keySeparator could be set to : in settings.json. When this setting is configured, the autocompletion feature would generate suggestions using the specified character.

Example:

With the setting "i18n-ally.keySeparator": ":"

And the following locale file:

{
  "vpc": {
    "key_0": "Please enter a valid CIDR block."
  }
}

The autocompletion should suggest vpc:key_0 instead of vpc.key_0.

Additional context
This feature would greatly improve the extension's flexibility to support various project conventions.

Here is a screenshot of the current behavior where it only suggests the dot (.) separated path: