* Make `async:true` the default for `invoke` calls (#3750)
* Switch away from native grpc impl. (#3728)
* Remove usage of the 'deasync' library from @pulumi/pulumi. (#3752)
* Only retry as long as we get unavailable back. Anything else continues. (#3769)
* Handle all errors for now. (#3781)
* Do not assume --yes was present when using pulumi in non-interactive mode (#3793)
* Upgrade all paths for sdk and pkg to v2
* Backport C# invoke classes and other recent gen changes (#4288)
Adjust C# generation
* Replace IDeployment with a sealed class (#4318)
Replace IDeployment with a sealed class
* .NET: default to args subtype rather than Args.Empty (#4320)
* Adding system namespace for Dotnet code gen
This is required for using Obsolute attributes for deprecations
```
Iam/InstanceProfile.cs(142,10): error CS0246: The type or namespace name 'ObsoleteAttribute' could not be found (are you missing a using directive or an assembly reference?) [/Users/stack72/code/go/src/github.com/pulumi/pulumi-aws/sdk/dotnet/Pulumi.Aws.csproj]
Iam/InstanceProfile.cs(142,10): error CS0246: The type or namespace name 'Obsolete' could not be found (are you missing a using directive or an assembly reference?) [/Users/stack72/code/go/src/github.com/pulumi/pulumi-aws/sdk/dotnet/Pulumi.Aws.csproj]
```
* Fix the nullability of config type properties in C# codegen (#4379)
This caching is enabled by wrapping the `secrets.Manager` returned by
`DefaultSecretsProvider.OfType` in an outer `secrets.Manager` that
cooperates with `stack.{Serialize,Deserialize}PropertyValue`. Ciphertext
is cached on a per-secret-instance basis (i.e. not a per-plaintext-value
basis). Cached ciphertext is only reused if the plaintext for the secret
value has not changed. Entries are inserted into the cache upon both
encryption and decryption so that values that originated from ciphertext
and that have not changed can aoid re-encryption.
Contributes to #3178.
Adds support for additional cloud secrets providers (AWS KMS, Azure KeyVault, Google Cloud KMS, and HashiCorp Vault) as the encryption backend for Pulumi secrets. This augments the previous choice between using the app.pulumi.com-managed secrets encryption or a fully-client-side local passphrase encryption.
This is implemented using the Go Cloud Development Kit support for pluggable secrets providers.
Like our cloud storage backend support which also uses Go Cloud Development Kit, this PR also bleeds through to users the URI scheme's that the Go CDK defines for specifying each of secrets providers - like `awskms://alias/LukeTesting?region=us-west-2` or `azurekeyvault://mykeyvaultname.vault.azure.net/keys/mykeyname`.
Also like our cloud storage backend support, this PR doesn't solve for how to configure the cloud provider client used to resolve the URIs above - the standard ambient credentials are used in both cases. Eventually, we will likely need to provide ways for both of these features to be configured independently of each other and of the providers used for resource provisioning.
