[i18n] add option to disable duplicate id check

[marcuskrahl]

Description and reproduction of the issue

Currently the i18n rule will always report errors when custom ids are used multiple times.

However there may be cases where this is not desired, for example when using common labels throughout the application

<button type="button" i18n="@@common.cancel-label">Cancel</button>

<!-- later in the same file-->

<button type="button" i18n="@@common.cancel-label">Cancel</button>

Angular already reports duplicate ids which do not have the same content. So an option should be introduced to disable the duplicate id check.

{
  "rules": {
    "@angular-eslint/template/i18n": ["warn"]
  }
}

Versions

package	version
@angular-eslint/eslint-plugin-template	13.0.1
@angular-eslint/template-parser	13.0.1
@typescript-eslint/parser	4.33.0
ESLint	7.32.0
node	14.18.2

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest supported version of the packages and checked my ng version output per the instructions given here.