Support mapping source paths in backtraces

#### Feature

GDB and LLDB have facilities for mapping source paths to address situations in which code was compiled in a different location from where the source is located on the machine it's run/debugged on. It'd be great to support this for Wasmtime backtraces, too.

#### Benefit

Making debugging of code compiled elsewhere easier.

#### Implementation

I'm not sure where exactly the search/replace would happen that'd lead to changed output. What I imagine for the user experience is something like a new (repeatable) CLI argument along the lines of `-D source-map [path-prefix]::[path]`

#### Alternatives

Doing nothing