Fix the following warning and turn on "treat warnings as errors" for our .NET projects.
```
Deployment/InvokeOptions.cs(6,60): warning CS1574: XML comment has cref attribute 'InvokeAsync{T}(string,
```
A regression was introduced when we added support for non-Node.js Pulumi programs to run Policy Packs. With that change, we now pass the Policy Pack's full path as the plugin's pwd (so that it would load the `@pulumi/pulumi/cmd/run-policy-pack` Node module from the Policy Pack's node_modules rather than the program's node_modules), but we also pass the path to the policy pack as well. If the path is a full rooted path, this would work fine, and that's what our tests do. However, if a relative path is specified, then it will be looking to load the Policy Pack relative to the pwd, which doesn't produce a correct path leading to failures trying to load the Policy Pack.
Since the pwd is the policy pack path, we can simply pass the path as `"."` to the analyzer plugin, and it will load the policy pack in its pwd.
This change adds support for setting `PULUMI_PREFER_YARN` to true to opt-in to preferring `yarn` over `npm` when installing Node.js dependencies (and publishing Policy Packs). If `PULUMI_PREFER_YARN` is truthy, but `yarn` cannot be found on `$PATH`, we fallback to using `npm`. If `npm` can't be found on `$PATH`, we provide a more helpful error message.
Add support for a test option that indicates that failed update steps
should be retried. Currently the maximum number of retries (3) is not
configurable.
* Reword step failure message prefix during an `update`
The text "Plan applied failed: " is pretty inscrutable given our
current system. While both "plan" and "apply" are concepts inside the
the implementation of the CLI, we usually talk in terms of `preview`
and `update`. I suspect there are some cases where this prefix is not
100% technically correct, and if there's a better short way of saying
something more correct, I would love to adopt that instead, but as is,
I would really love to get rid of the "Plan apply failed" text in our
system, it pains me every time I read it.
* Do not prefix failed operation errors.
The text "Plan applied failed: " is pretty inscrutable given our
current system. While both "plan" and "apply" are concepts inside the
the implementation of the CLI, we usually talk in terms of `preview`
and `update`. I suspect there are some cases where this prefix is not
100% technically correct, and if there's a better short way of saying
something more correct, I would love to adopt that instead, but as is,
I would really love to get rid of the "Plan apply failed" text in our
system, it pains me every time I read it.
The test files are currently included in the npm package, and we have packages that depend on the test files currently, so when installing the linkable `@pulumi/pulumi` package locally, don't delete the tests.
Codepaths which could result in a hang will print a message to the console indicating the problem, along with a link to documentation on how to restructure code to best address it.
`StackReference.getOutputSync` and `requireOutputSync` have been deprecated as they may cause hangs on some combinations of Node and certain OS platforms. `StackReference.getOutput` and `requireOutput` should be used instead.
Fixes building grpc package with gcc8 and newer
Fixes building grpc package for node 13.x
Matches minor grpc release (1.24.x) to version used by dotnet sdk
To allow Policy Packs to run against Pulumi programs written in all languages, we now look for the `@pulumi/pulumi/cmd/run-policy-pack` module in the Policy Pack's node_modules (instead of in the Pulumi program's node_modules; which doesn't exist for non-node languages). The `@pulumi/policy` library that a Policy Pack will depend on should already depend on a recent enough version of `@pulumi/pulumi`. When we can't find the module, it's more likely it's due to the dependencies for the Policy Pack not being installed. Provide a more helpful error message in this case.
If the algorithm is unspecified, we provide a reasonable default. If an
alternative is provided (via an undocumented route), we use that,
however.
This commit brings us into line with the documentation.
Fixes#3359.
