Generate adaptive cards for API plugins in separate files

[maisarissi]

Related to: OfficeDev/teams-toolkit#12665

Once TTK supports adaptive cards in separate files, Kiota should generate the adaptive cards for each function in a separate file and add the reference that of the generated files in the API Plugin:

"functions": [
    {
        "name": "search_issues_and_pull_requests",
        "description": "Find issues by state and keyword. This method returns up to 100 results [per page](https://docs.gith",
        "capabilities": {
            "response_semantics": {
                "data_path": "$.items",
                "properties": {
                    "title": "$.title",
                    "subtitle": "$.body",
                    "url": "$.url"
                },
                "static_template": "$[file('search_issues_and_pull_requests_ad.json')]"
            }
        }
    },
    {
        "name": "another_function",
        "description": "Another function",
        "capabilities": {
            "response_semantics": {
                "data_path": "$",
                "properties": {
                    "title": "$.title",
                    "subtitle": "$.id",
                    "url": "$.url"
                },
                "static_template": "$[file('another_function_ad.json')]"
            }
        }
    },
]