Set a local storage url for update (Recommendation Setting)

Default policy is empty. This policy depends on AU2_DeploySpecificVersion, if AU2_DeploySpecificVersion is empty, AU2_Update3rdStorageUrl will not work. Stored installation package needs to be named according to the following rules: ZoomInstallerFull.msi, x64_ZoomInstallerFull.msi, winarm64_ZoomInstallerFull.msi. If the user's installation package can be downloaded through such a link: "http://127.0.0.1/x64_ZoomInstallerFull.msi", this string should be "http://127.0.0.1". If this policy is a valid string, client will use this string as the update download url when the target version of the update is specified. If this policy is not set, client will use the default setting.