The language server needs stdin, and for tests we should be passing it
around. My intent is to pass in a faux stdin to Driver for language
server tests.
As long as I'm adding a new parameter, I was looking at also changing
the way streams are passed in to Driver for style (pointers since
they're held past construction lifetime). Since these are all stored in
DriverEnv, I thought it might be a net improvement to use the struct
directly, getting more explicit parameter names and also removing the
need for `SetFuzzing`.
I'm trying here to avoid functional changes, but there are a couple
additional fixes like removing an obsolete `find_insensitive` and
refactoring how `ValidateOptions` handles errors (because it reduces the
number of spots that operate on error_stream).
Removes the separate language server binary; I'm not sure we need to
provide it. Instead, `carbon language-server` is added as a subcommand.
Moves //language_server to //toolchain/language_server. Splits into a
trivial language_server.h, and a substantive server.h. I wasn't sure
about a better name, but wanted the split similar to check/check.h,
lex/lex.h, etc. At the same time, the class is probably going to be a
little big so not a good fit to through into just a cpp file.
This fixes some style issues with the language server class, but
generally I'm trying to not address things here in order to keep it
simpler.