meta: rename pip_install_wheel.bbclass to python_pep517.bbclass

pip_install_wheel shouldn't restricted to just using Pip to install
wheels (the installer module is simplier and likely a better option),
and in the future may be extended to also provide do_compile() using
the build module.

(From OE-Core rev: 3bdf64b97facce9706cc579bdbc9a80e0d48428f)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/python3-flit-core_3.7.1.bb

@@ -21,7 +21,7 @@ PYPI_PACKAGE = "flit"
 PEP517_SOURCE_PATH = "${S}/flit_core"
 
 do_install:class-native () {
-    pip_install_wheel_do_bootstrap_install
+    python_pep517_do_bootstrap_install
 }
 
 PACKAGES =+ "${PN}-tests"