Add labels from env for all tests in a run

#### I'm submitting a ...
- [ ] bug report
- [x] feature request
- [ ] support request => Please do not submit support request here, see note at the top of this template.

#### What is the current behavior?
Currently there is no way to pass environment-related info into all tests in a run without modifying the code base of the tests.

#### What is the expected behavior?
Allure should automatically convert environment variables to labels using the naming convention specified below.

#### What is the motivation / use case for changing the behavior?
It\`s useful to test an application or library across multiple different environments. Such environments may differ in
- a language version
- an operating system
- a platform
- a dependency version
- etc.

The environment-based labels help to distinguish test results produced by the same test in different environments. TestOps can group those results apart with its `env from label` feature.

#### Other information

##### Naming convention
Every environment variable in form `ALLURE_LABEL_=` is translated into the label `` with the value ``.
The label is added for each test in the run.

##### Constraints
To ensure consistency across different allure adapters the following constraints are imposed:
- The environment variables are captured when the test is about to start (see [allure-java](https://github.com/allure-framework/allure-java/blob/e91fb588572ed9397911e988035bc000cd93b354/allure-junit-platform/src/main/java/io/qameta/allure/junitplatform/AllureJunitPlatform.java#L509))

##### Example
Given the following environment variables:
```
ALLURE_LABEL_PYTHON_VERSION=3.11
ALLURE_LABEL_OS=Linux
ALLURE_LABEL_USERNAME=John
ALLURE_LABEL_EMPTY=
```

When the tests are run.

Then the following labels are present in any `*-result.json` file created during the run:
```json
{
...
"labels": [
...
{
"name": "PYTHON_VERSION",
"value": "3.11"
},
{
"name": "OS",
"value": "Linux"
},
{
"name": "USERNAME",
"value": "John"
},
{
"name": "EMPTY",
"value": ""
}
]
}
```

Commencez par examiner la référence de synchronisation des labels d’environnement dans allure-junit-platform/src/main/java/io/qameta/allure/junitplatform/AllureJunitPlatform.java ainsi que les points d’entrée des adaptateurs Python qui créent des fichiers JSON de résultats. Exécutez les tests existants des adaptateurs, puis vérifiez que chaque résultat de test reçoit des variables ALLURE_LABEL_, y compris pour les valeurs vides, avec les noms et les valeurs de labels attendus.

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