oe-debuginfod: add option for data storage

Storing the data files under $HOME can be unreliable if debuginfod
is used for several projects, especially if $HOME is shared
between machines.  We provide an option to save files under the
project directory.  The default behavior is unchanged.

Signed-off-by: Joe Slater <joe.slater@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>