Use URL as archive source when creating functions/packages

Previously, the CLI tends to download the file and upload it to internal storagsvc to persist when a user provides URL as archive source while creating the package. This approach increases the total package creation time if the file size is large.

With 1.7.0+, the CLI embeds the given URL in package archive directly. This approach brings couple benefits:

• Shorten package creation time.
• Increase the portability of fission spec file.

$ fission pkg create --spec --name dummy-package2 --env nodejs \
    --code https://raw.githubusercontent.com/fission/examples/main/nodejs/hello.js

which results in:

apiVersion: fission.io/v1
kind: Package
metadata:
  creationTimestamp: null
  name: dummy-package2
  namespace: default
spec:
  deployment:
    checksum: {}
    type: url
    url: https://raw.githubusercontent.com/fission/examples/main/nodejs/hello.js
    ....

You will notice the CLI still tends to download the file in order to generate the SHA256 checksum to prevent the file changed.

Downloading file to generate SHA256 checksum. To skip this step, please use --srcchecksum / --deploychecksum / --insecure.

You can either use --srcchecksum or --deploychecksum or --insecure to bypass the download steps.