[Module Proposal]: `avm/res/code-signing/code-signing-account`

### Check for previous/existing GitHub issues/module proposals

- [x] I have checked for previous/existing GitHub issues/module proposals.

### Check this module doesn't already exist in the module indexes

- [x] I have checked for that this module doesn't already exist in the module indexes.

### Bicep or Terraform?

Bicep

### Module Classification?

Resource Module

### Module Name

avm/res/code-signing/code-signing-account

### Module Details

I searched as much as possible and tried to find an AVM module for Azure Artifact Signing (aka Azure Trusted Signing) (aka Microsoft.CodeSigning) but was not able to find one.

We'd like to include the creation of our Azure Artifact Signing in IaC by using an AVM module.

https://learn.microsoft.com/en-us/azure/artifact-signing/

Resource reference: https://learn.microsoft.com/en-us/azure/templates/microsoft.codesigning/codesigningaccounts?pivots=deployment-language-bicep

### Do you want to be the owner of this module?

No

### Module Owner's GitHub Username (handle)

_No response_

### (Optional) Secondary Module Owner's GitHub Username (handle)

_No response_

Start with the Azure Artifact Signing documentation and the Microsoft.CodeSigning/codesigningaccounts resource reference linked in the issue. Compare the resource requirements with existing AVM Bicep resource modules; done means an AVM module for avm/res/code-signing/code-signing-account is created and available in the module indexes.

Written by the indexing model from the issue text.