Code improvements / Fix warnings

- Fix CodeQL warnings
- Port lots of improvements/fixes from PR #225
- replace 'array_hexstr' and '%*H' format by sdk function 'format_hex'
- Add 'noreturn' attribute in 'main.c'

src_bagl/ui_flow_signMessage712.c

@@ -57,7 +57,7 @@ UX_STEP_INIT(
 UX_STEP_CB(
     ux_712_step_approve,
     pb,
-    ui_712_approve(NULL),
+    ui_712_approve(),
     {
       &C_icon_validate_14,
       "Approve",
@@ -65,7 +65,7 @@ UX_STEP_CB(
 UX_STEP_CB(
     ux_712_step_reject,
     pb,
-    ui_712_reject(NULL),
+    ui_712_reject(),
     {
       &C_icon_crossmark,
       "Reject",