[Feature] Add option to specify `cmake.buildDirectory` for single- and multi-config generators, respectively

## Problem Description

In CMake Generator, there are **single-** and **multi-config** generator to choose. If we use **single-config**, such as `MinGW Makefiles`, I would like to separate build directories for **Configurations** and **Architectures**. Thanks to the [Substitution Variable](https://github.com/microsoft/vscode-cmake-tools/blob/main/docs/cmake-settings.md#variable-substitution) provided by CMake-Tools, we can design our custom build directory.

### 1. Single-Config Generator

If I use **single-config** Generator, for example `MinGW Makefiles` or `NMake Makefiles`, one **Makefile** file only supports one configuration. So in order to differentiate **Debug** and **Release** configurations, I will set `cmake.buildDirectory` like this:

```json
{
"cmake.buildDirectory":
"${workspaceFolder}/build/${buildKitTargetOs}-${buildKitVendor}-${buildKitTargetArch}-${buildType}"
}
```

The possible results of build directories will look like this:

```
build/
win32-MSVC-x64-Debug/
win32-MSVC-x64-Release/
win32-MSVC-x86-Debug/
win32-MSVC-x86-Release/
win32-GCC-x86-Debug/
win32-GCC-x86-Release/
win32-GCC-x86-MinSizeRel/
```

### 2. Multi-Config Generator

However, if I choose to use **multi-config** generators such as `Ninja Multi-Config`, it is a waste to separate different configurations into individual sub-folders. So I will delete `${buildType}` variable from the **single-config** format. Here is my format of `cmake.buildDirectory`:

```json
{
"cmake.buildDirectory":
"${workspaceFolder}/build/${buildKitTargetOs}-${buildKitVendor}-${buildKitTargetArch}"
}
```

The possible results of build directories will look like:

```bash
build/
win32-MSVC-x64/
win32-MSVC-x86/
win32-GCC-x64/
win32-GCC-x86/
```

## Expected Setting

I hope CMake-Tools can give us an option to set `cmake.buildDirectory` for **single-config** and **multi-config**, respectively. And Then CMake-Tools will **auto-detect** which type our currently-used generator belongs to, **single-config** or **multi-config**.

For example:

```json
{
"cmake.buildDirectory": {
"singleConfig": "${workspaceFolder}/build",
"multiConfig": "${workspaceFolder}/build",
}
}
```

Of course, we can still retain the original format of `cmake.buildDirectory`. That means both **single-** and **multi-config** will use the same format of `cmake.buildDirectory`:

```json
{
"cmake.buildDirectory": "${workspaceFolder}/build/${buildKitHostOs}_${buildKitTargetOs}"
}
```

In my case, I would like to set this settings like this:

```json
{
"cmake.buildDirectory": {
"singleConfig":
"${workspaceFolder}/build/${buildKitTargetOs}-${buildKitVendor}-${buildKitTargetArch}-${buildType}",
"multiConfig":
"${workspaceFolder}/build/${buildKitTargetOs}-${buildKitVendor}-${buildKitTargetArch}"
}
}
```

## Platform and Version:

- **Visual Studio Code Version:** 1.65.2
- **CMake Tools Version:** 1.9.2
- **CMake Version:** 3.21.2