flash/bluenrg-x: support programming without loader

flash/bluenrg-x: support programming without loader

fallback programming without loader when resources are not available
while at there refactor reused code
(wait for interrupt and command execution)

Change-Id: I2cba0f53d3470bc324f4a72614c236cebf196f64
Signed-off-by: BOCHKATI Tarek <tarek.bochkati@st.com>
Signed-off-by: HAOUES Ahmed <ahmed.haoues@st.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8883
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>