Merge recent doc changes for OEMCrypto

This is a cherry pick of recent changes to OEMCrypto and ODK. Most of
these are part of the document migration to doxygen.

See http://go/wvgerrit/106005 and its parents for code reviews.

Bug: 144715340
Bug: 148232693
Bug: 167580674
Change-Id: I658f99c8117b974faed97322d61fac0f382283af

libwvdrmengine/oemcrypto/test/oemcrypto_test_main.cpp

@@ -4,6 +4,7 @@
 #include "OEMCryptoCENC.h"
 #include "log.h"
 #include "oec_device_features.h"
+#include "oemcrypto_corpus_generator_helper.h"
 #include "test_sleep.h"
 
 static void acknowledge_cast() {
@@ -23,6 +24,9 @@ int main(int argc, char** argv) {
   // Skip the first element, which is the program name.
   const std::vector<std::string> args(argv + 1, argv + argc);
   for (const std::string& arg : args) {
+    if (arg == "--generate_corpus") {
+      wvoec::SetGenerateCorpus(true);
+    }
     if (arg == "--verbose" || arg == "-v") {
       ++verbosity;
     } else if (arg == "--cast") {