Download non-prerelease extensions ONLY by default

[Ebsan]

Takes care of #31 and downloads only non-prerelease versions of extensions.

Some other updates are:

• Removed use of storing sessions with session = requests.session() in favor of using the the http method directly from the requests object. This was an attempt to fix Failure while fetching extensions. #33.
• Added the --prerelease-extensions toggle to allow user to download prerelease extensions as well
• Added the --vscode-version arg to configure version used in User-Agent header. Defaults to 1.69.2, the latest version of VSCode as of today

[Ebsan]

This pull will cause issues for #24 because only one version of the latest non-prerelease extension will be downloaded. Logic needs to be added to download all the targetTypes of the latest version. Use redhat.java as a good example.

POST
{
    "filters": [
        {
            "criteria": [
                {
                    "filterType": 10,
                    "value": "redhat.java"
                },
                {
                    "filterType": 8,
                    "value": "Microsoft.VisualStudio.Code"
                },
                {
                    "filterType": 12,
                    "value": "4096"
                }
            ],
            "pageNumber": 1,
            "pageSize": 50,
            "sortBy": 0,
            "sortOrder": 0
        }
    ],
    "assetTypes": [],
    "flags": 950
}

[tomer953]

Hi,

I advise to test the removal of the requests sessions, this should increase performence.
however, when requests fails we can use some retry mechanisem, for instance:

from requests.adapters import HTTPAdapter, Retry

retries = Retry(total=5, backoff_factor=1, status_forcelist=[ 413, 429, 500, 501, 502, 503, 504,  ], allowed_methods=["HEAD", "GET", "PUT", "DELETE", "OPTIONS", "TRACE"])
session = requests.session()
session.mount('https://', HTTPAdapter(max_retries=retries))
# session.get(...)

[Ebsan]

@tomer953 I will test your recommendation in another pull request. I can probably run some timed tests for the different requests solutions as well in that pull request.

[LOLINTERNETZ]

Comments in #31