replace the build system with meson

replace the build system with meson

Meson is a modern build system that has seen a rise in adoption and some
version of it is available in almost every platform supported.

Compared to automake, meson has the following advantages:

* Meson provides a significant boost to the build and configuration time
  by better exploiting parallelism.

* Meson is subjectively considered to be better in readability.

These merits alone justify experimenting with meson as a way of
improving development time and ergonomics. However, there are some
compromises to ensure the transition goes relatively smooth:

* The system tests currently rely on various files within the source
  directory. Changing this requirement is a non-trivial task that can't
  be currently justified. Currently the last compiled build directory
  writes into the source tree which is in turn used by pytest.

* The minimum version supported has been fixed at 0.61. Increasing this
  value will require choosing a baseline of distributions that can
  package with meson. On the contrary, there will likely be an attempt
  to decrease this value to ensure almost universal support for building
  BIND 9 with meson.