cmake: linker generator: Add MIN/MAX_SIZE to zephyr_linker_section()

Add MIN_SIZE and MAX_SIZE options to zephyr_linker_section()
and zephyr_linker_section_configure().
This allows padding (for MIN_SIZE) and link-time checking (for MAX_SIZE)
of sections (and parts of sections).

Clarify comments for zephyr_linker_section_configure

Signed-off-by: Björn Bergman <bjorn.bergman@iar.com>