[Feature]: Need a way to set up extendedproperty by Set-AzEnvironment

### Description of the new feature
```
PS C:\Azure\upstream\azure-powershell> (Get-AzEnvironment).ExtendedProperties

Key Value
--- -----
OperationalInsightsEndpoint https://api.loganalytics.us/v1
AzureSynapseAnalyticsEndpointSuffix dev.azuresynapse.usgovcloudapi.net
AzureAnalysisServicesEndpointSuffix asazure.usgovcloudapi.net
MicrosoftGraphEndpointResourceId https://graph.microsoft.us/
ManagedHsmServiceEndpointSuffix managedhsm.usgovcloudapi.net
OperationalInsightsEndpointResourceId https://api.loganalytics.us
AnalysisServicesEndpointResourceId https://region.asazure.usgovcloudapi.net
ManagedHsmServiceEndpointResourceId https://managedhsm.usgovcloudapi.net
AzureSynapseAnalyticsEndpointResourceId https://dev.azuresynapse.usgovcloudapi.net
MicrosoftGraphUrl https://graph.microsoft.us
ContainerRegistryEndpointResourceId https://management.usgovcloudapi.net
OperationalInsightsEndpoint https://api.loganalytics.azure.cn/v1
AzureSynapseAnalyticsEndpointSuffix dev.azuresynapse.azure.cn
AzureAnalysisServicesEndpointSuffix asazure.chinacloudapi.cn
MicrosoftGraphEndpointResourceId https://microsoftgraph.chinacloudapi.cn/
ManagedHsmServiceEndpointSuffix managedhsm.azure.cn
OperationalInsightsEndpointResourceId https://api.loganalytics.azure.cn
AnalysisServicesEndpointResourceId https://region.asazure.chinacloudapi.cn
ManagedHsmServiceEndpointResourceId https://managedhsm.azure.cn
AzureSynapseAnalyticsEndpointResourceId https://dev.azuresynapse.azure.cn
MicrosoftGraphUrl https://microsoftgraph.chinacloudapi.cn
ContainerRegistryEndpointResourceId https://management.chinacloudapi.cn
ManagedHsmServiceEndpointResourceId https://managedhsm.azure.net
ContainerRegistryEndpointResourceId https://management.azure.com
AzureAppConfigurationEndpointResourceId https://azconfig.io
AzurePurviewEndpointSuffix purview.azure.net
ManagedHsmServiceEndpointSuffix managedhsm.azure.net
MicrosoftGraphUrl https://graph.microsoft.com
AzureAttestationServiceEndpointSuffix attest.azure.net
AzureSynapseAnalyticsEndpointSuffix dev.azuresynapse.net
AzureAnalysisServicesEndpointSuffix asazure.windows.net
AzureSynapseAnalyticsEndpointResourceId https://dev.azuresynapse.net
OperationalInsightsEndpointResourceId https://api.loganalytics.io
AnalysisServicesEndpointResourceId https://region.asazure.windows.net
AzurePurviewEndpointResourceId https://purview.azure.net
AzureAppConfigurationEndpointSuffix azconfig.io
AzureAttestationServiceEndpointResourceId https://attest.azure.net
MicrosoftGraphEndpointResourceId https://graph.microsoft.com/
OperationalInsightsEndpoint https://api.loganalytics.io/v1
```
If I want to change the value of ManagedHsmServiceEndpointSuffix, the only thing I can do is modifying AzureRmContext.json manually.

### Proposed implementation details (optional)

Support `Set-AzEnvironment -ExtendedProperty -Key xxx -Value xxx`

Start by locating the Set-AzEnvironment implementation and the handling of Environment.ExtendedProperties, then inspect how values are persisted in AzureRmContext.json. Done means Set-AzEnvironment accepts an extended-property key and value and updates the corresponding environment property without manual file editing.

Written by the indexing model from the issue text.