Params refactor, simplified (#2300)

* always c++

* Create C++ params class

* get works

* tests hang now

* passes tests

* cleanup string formatting

* handle interrupt in blocking read

* fix memory leak

* remove unused constructor

* Use delete_db_value directly

* Rename put -> write_db_value

* filename cleanup

* no semicolons in cython

* Update common/SConscript

Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>

* add std::string version of delete_db_value

* This is handled

* cleanup encoding

* Add clear method to clear all

* add persistent params

* fix android build

* Should be called clear_all

* only import params when needed

* set params path on manager import

* recusrively create directories

* Fix function order

* cleanup mkdirp

Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>
Co-authored-by: Comma Device <device@comma.ai>
old-commit-hash: 2e182e5c57

common/SConscript

@@ -4,3 +4,11 @@ Import('env', 'cython_dependencies')
 env.Command(['common_pyx.so', 'clock.cpp'],
             cython_dependencies + ['common_pyx_setup.py', 'clock.pyx'],
             "cd common && python3 common_pyx_setup.py build_ext --inplace")
+
+# Build cython params module
+env.Command(['params_pyx.so', 'params_pyx.cpp'],
+            cython_dependencies + [
+                'params_pyx_setup.py', 'params_pyx.pyx', 'params_pxd.pxd',
+                '#selfdrive/common/params.cc', '#selfdrive/common/params.h',
+                '#selfdrive/common/util.c', '#selfdrive/common/util.h'],
+            "cd common && python3 params_pyx_setup.py build_ext --inplace")