incorrect behavior of dotnet package

### Description

The command line help lies about the syntax for adding a nugget package. It says, the command should be:
```dotnet package add BenchmarkDotNet```
which does not work and produces an error.

You have to use
```dotnet add package BenchmarkDotNet``` instead.

### Reproduction Steps

```shell
md TestProject
cd TestProject
dotnet new console
dotnet package add BenchmarkDotNet
```

### Expected behavior

According the command line help, it should install the nugget package.

See `dotnet package -?` prints
```
Description:

Usage:
dotnet package [command] [options]

Options:
-?, -h, --help Show command line help.

Commands:
search ...
add ...
list ...
remove ...
```

### Actual behavior

Error is reported
```Could not find project or directory ``.```

### Regression?

unknown

### Known Workarounds

Disobey the command line help, and swap the command `add` with the `package` keyword:
```shell
dotnet add package BenchmarkDotNet
```
> EDIT
> or specify the project path or file (thx @baronfel):
> ```shell
> dotnet package add BenchmarkDotNet --project .
> ```

### Configuration

.net 9.0.304
Windows 11 Enterprise 23H2 (OS Build 22631.5840)
x64

### Other information

_No response_

Start by running `dotnet package -?` and the reproduction commands in a fresh console project to compare the advertised and accepted syntax. Trace the CLI help and package-add entry point, then verify that the help matches the supported invocation and that the reproduction no longer reports a missing project or directory.

Written by the indexing model from the issue text.