core: Add basic reserved keywords

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
core: add basic reserved-keywords API

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
tests: add tests for reserved keywords

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
core: implement reserved keywords logic

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>