Add LLDB init commands for running on Windows

[adam-fowler]

It looks like Swift LLDB on Windows requires the swiftCore.dll to be loaded before running the debugger. The following lldb command does this

process load <path to swiftCore.dll>

This can be added in the initCommands section to the launch configs built in createExecutableConfigurations and createTestConfiguration or by setting the initCommands field in the LLDB configuration settings.

[compnerd]

Correction to this - it seems to also be the missing SDK settings. So this should include settings set target.sdk-path <SDKROOT>.

[adam-fowler]

Resolved in #275