codeparser: Track appendVar and prependVar calls as we do for getVar

We need to track appendVar and prependVar calls just as we do for getVar in order
to ensure we're not missing variable dependencies.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
codeparser: Track bb.utils.contains usage

The bb.utils.contains function usage is getting increasingly used in the metadata
but isn't handled automatically by the python dependency tracking code. This patch
changes that and also adds the "OE" names for the functions.

Whilst there are reasons this is a bad idea, its likely outweighed by the
shear number of these references and the current holes in dependency information
which we're now relying heavily upon.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>