msgs, ccgstmts: fixes #11572 (#11621)

* [refactor] msgs: toFilename now return just the filename

The C codegen uses just the file name for stacktrace when
excessiveStackTrace is off (see quotedName),
so there aren't any reason for other codegen to not do the same.

The file name is now cached in TFileInfo.shortName, which was introduced
for nimsuggest, and went unused after several refactoring of the
compiler.

A toProjPath() proc has been added for the previous behavior of
toFilename().

* ccgstmt: use quotedFilename() for raiseExceptionEx

This is the same proc used for stacktrace when --stacktrace:on

Fixes #11572

* msgs: handle case where file name is not available

compiler/ccgstmts.nim

@@ -690,7 +690,7 @@ proc genRaiseStmt(p: BProc, t: PNode) =
       lineCg(p, cpsStmts, "#raiseExceptionEx((#Exception*)$1, $2, $3, $4, $5);$n",
           [e, makeCString(typ.sym.name.s),
           makeCString(if p.prc != nil: p.prc.name.s else: p.module.module.name.s),
-          makeCString(toFileName(p.config, t.info)), toLinenumber(t.info)])
+          quotedFilename(p.config, t.info), toLinenumber(t.info)])
       if optNimV2 in p.config.globalOptions:
         lineCg(p, cpsStmts, "$1 = NIM_NIL;$n", [e])
   else: