[build] Move to python build scripts per module

This change moves Bonnibel from a separate project into the jsix tree,
and alters the project configuration to be jsix-specific. (I stopped
using bonnibel for any other projects, so it's far easier to make it a
custom generator for jsix.) The build system now also uses actual python
code in `*.module` files to configure modules instead of TOML files.
Target configs (boot, kernel-mode, user-mode) now moved to separate TOML
files under `configs/` and can inherit from one another.

configs/rules.ninja

@@ -0,0 +1,75 @@
+# This file is automatically generated by bonnibel
+
+rule compile_c
+  command = $cc -MMD -MF $out.d $cflags $ccflags -o $out -c $in
+  description = Compiling $name
+  depfile = $out.d
+  deps = gcc
+
+rule dump_c_defs
+  command = echo | $cc $ccflags $cflags -dM -E - > $out
+  description = Dumping C defines for $target
+
+rule dump_c_run
+  command = echo '#!/bin/bash' > $out; echo '$cc $ccflags $cflags $$*' >> $
+      $out; chmod a+x $out
+  description = Dumping C arguments for $target
+
+rule compile_cxx
+  command = $cxx -MMD -MF $out.d $cxxflags $ccflags -o $out -c $in
+  description = Compiling $name
+  depfile = $out.d
+  deps = gcc
+
+rule dump_cpp_defs
+  command = echo | $cxx -x c++ $ccflags $cxxflags -dM -E - > $out
+  description = Dumping C++ defines for $target
+
+rule dump_cpp_run
+  command = echo '#!/bin/bash' > $out; echo '$cxx $ccflags $cxxflags $$*' $
+      >> $out; chmod a+x $out
+  description = Dumping C++ arguments for $target
+
+rule compile_asm
+  command = $nasm -o $out -felf64 -MD $out.d $asflags $in
+  description = Assembling $name
+  depfile = $out.d
+  deps = gcc
+
+rule parse_cog
+  command = $cog -o $out -d $cogflags $in
+  description = Parsing $name
+
+rule exe
+  command = $ld $ldflags -o $out $in $libs
+  description = Linking $name
+
+rule lib
+  command = $ar qcs $out $in
+  description = Archiving $name
+
+rule cp
+  command = cp $in $out
+  description = Copying $name
+
+rule dump
+  command = objdump -DSC -M intel $in > $out
+  description = Dumping decompiled $name
+
+rule makest
+    description = Making symbol table
+    command = nm -n -S --demangle $in | ${source_root}/scripts/build_symbol_table.py $out
+
+rule makefat
+    description = Creating $name
+    command = $
+        cp $in $out; $
+        mcopy -s -D o -i $out@@1M ${build_root}/fatroot/* ::/
+
+rule strip
+    description = Stripping $name
+    command = $
+        cp $in $out; $
+        objcopy --only-keep-debug $out $debug; $
+        strip -g $out; $
+        objcopy --add-gnu-debuglink=$debug $out