Diagram/table: keyspace & key-value associations

[cwgoes]

Table or map out the keyspace utilized by the IBC handler module & what is stored where.

[cwgoes]

Should this be done in each ICS or in a single table somewhere? If the latter, where?

[cwgoes]

For now it will go in ICS 24, which introduces bidirectional dependency, oh well.

[gjermundgaraba]

This issue was mistakenly reopened during some integration work, so closing again now.