pjsip configuration: Make transport TOS values consistent with endpoints

Transport TOS values were interpreted as DSCP values without being documented
as such. Endpoint TOS values (tos_audio/tos_video) behaved normally as TOS
values have historically. This patch makes the transport TOS values behave as
TOS values and makes all TOS values readable as string values (e.g. AF11).
In addition, alembic scripts have been updated to use the proper field types
for all TOS/COS values.

(issue ASTERISK-23235)
Reported by: George Joseph
Review: https://reviewboard.asterisk.org/r/3304/
........

Merged revisions 410028 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@410029 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/acl.h

@@ -357,6 +357,17 @@ int ast_str2tos(const char *value, unsigned int *tos);
  */
 const char *ast_tos2str(unsigned int tos);
 
+/*!
+ * \brief Convert a TOS value into its string representation
+ *        and create a dynamically allocated copy
+ *
+ * \param tos The TOS value to look up
+ * \param buf pointer to character pointer where string will be duplicated to
+ *
+ * \note The string allocated at buf must be free'd
+ */
+void ast_tos2str_buf(unsigned int tos, char **buf);
+
 /*!
  * \brief Retrieve a named ACL
  *