devtool: new ide plugin

The new devtool ide plugin configures an IDE to work with the eSDK.

With this initial implementation VSCode is the default IDE.
The plugin works for recipes inheriting the cmake or the meson bbclass.
Support for more programming languages and build tools may be added in
the future.

Using the plugin in recipe modes:
$ devtool modify a-recipe
$ devtool ide a-recipe a-image
$ code "$BUILDDIR/workspace/sources/a-recipe"
Work in VSCode, after installing the proposed plugins

Using the plugin without a recipe
$ devtool ide none a-image
vscode where/the/sources/are
Use the cross tool-chain which is provided as a cmake-kit.

The goal of this implementation is to create a configuration for VSCode
(or other IDEs) that allows to work on the code of a recipe completely
independent from bitbake. bitbake is only called if the configuration or
the whole SDK has to be regenerated. But bitbake should not need to be
called while working in the IDE. This has two major advantages over
calling devtool build from the IDE:
- The IDE provides plugins for integration with cmake, for example.
  These features are usable, which would not be the case if bitbake or
  devtool are called from within the IDE.
- It is much faster.

Signed-off-by: Adrian Freihofer <[email protected]>