[Driver] [Modules] Support -fmodule-output (1/2)

Patches to support the one-phase compilation model for modules.

The behavior:
(1) If -o and -c is specified , the module file is in the same path
within the same directory as the output the -o specified and with a new
suffix .pcm.
(2) Otherwise, the module file is in the same path within the working
directory directory with the name of the input file with a new suffix
.pcm

For example,

```
Hello.cppm Use.cpp
```

A trivial one and the contents are ignored. When we run:

```
clang++ -std=c++20 -fmodule-output Hello.cppm -c
```

The directory would look like:

```
Hello.cppm  Hello.o  Hello.pcm Use.cpp
```

And if we run:

```
clang++ -std=c++20 -fmodule-output Hello.cppm -c -o output/Hello.o
```

Then the `output` directory may look like:

```
Hello.o  Hello.pcm
```

Reviewed By: dblaikie, iains, tahonermann

Differential Revision: https://reviews.llvm.org/D137058