Update doxygen and fix documentation (#5106)

Update Doxyfile to version 1.9.1

Re-enable doxygen CI checker

Fix some regular comments that should have been doc comments

Document void return types for some inline functions explicitly

Move start of some doxygen groups so they are included always, and not left
out of certain ifdefs

Ignore some doxygen warnings:
    Member (function) is not documented in headers
    Documented empty return type in headers
    Argument has multiple @param documentation sections

JerryScript-DCO-1.0-Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

jerry-core/jcontext/jcontext.c

@@ -45,6 +45,8 @@ jcontext_has_pending_abort (void)
 
 /**
  * Set the abort flag for the context.
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 jcontext_set_abort_flag (bool is_abort) /**< true - if the abort flag should be set
@@ -64,6 +66,8 @@ jcontext_set_abort_flag (bool is_abort) /**< true - if the abort flag should be
 
 /**
  * Set the exception flag for the context.
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 jcontext_set_exception_flag (bool is_exception) /**< true - if the exception flag should be set
@@ -81,6 +85,8 @@ jcontext_set_exception_flag (bool is_exception) /**< true - if the exception fla
 
 /**
  * Raise exception from the given error value.
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 jcontext_raise_exception (ecma_value_t error) /**< error to raise */