meta: replace cmake mono-build system with a custom build co-ordinator

every system component now has its own self-contained build system, and a
seed file describing the component and its build system and dependencies.

a new tool, meadow, collects and uses these seed files to build the
components into a full system. meadow also manages the target system root
and a host prefix where toolchain tools are installed to.

the build system has also been updated to use a new $ARCH-rosetta-gcc
compiler, and the patches files necessary to build it have been
added to toolchain/cross-compiler.

.gitignore

@@ -243,7 +243,6 @@ docs/_build/
 
 # PyBuilder
 .pybuilder/
-target/
 
 # Jupyter Notebook
 .ipynb_checkpoints
@@ -341,5 +340,6 @@ pyrightconfig.json
 
 # End of https://www.toptal.com/developers/gitignore/api/c,vim,linux,macos,windows,cmake,python
 
-build*
+build
+build-native
 .cache