Main changes

• __TS__originalTraceback is able to save two types of source maps.
  First type is default: Record<number, number> lua line is being mapped into TS line.
  The second type is: Record<number, { line : number, file: string }: lua line is mapped into TS line and source file name.
  The first type has been already applied to single file compilation. And I have applied the second type for bundle compilation. The reason -- in bundle mode runtime Lua should know about target file (because bundle filename != source file)
• I have added printStackTraceBundleOverride function into bundle.ts. This function generates the second type of source map.
• LuaPrinter's method printFile will not generate {#SourceMapTraceback} in bundle mode anymore. Because Source Map Traceback should be constructed for the whole bundled file
• getBundleResult function inserts the traceback before the entryPoint

Misc changes

• Moved {#SourceMapTraceback} magic-macro-string into a static field sourceMapTracebackPlaceholder of LuaPrinter class
• Haven't touched sourceMapNode in moduleSourceNode (because it is not necessary)
• Moved helpful lineAndColumnOf from test\unit\printer\sourcemaps.spec.ts into test\unit\printer\utils.ts

Tests coverage

• Moved default bundle test into bundle/bundle-two-files
• Tested source map generation with bundle/bundle-source-maps test
• Both tests are located in test\transpile\bundle.spec.ts and wrapped into describe