Macros for C and Java bindings.

[cobward]

• Adds macros to improve the binding definitions for C and Java.
• Also adds prepare and complete to the C and Java APIs.

[CLAassistant]

All committers have signed the CLA.

[sbihel]

Merged main to use latest ssi (0.7.0). CI is failing but for the same reason as for previous commits

[sbihel]

Java 1.7 not supported anymore apparently, will investigate

[sbihel]

Closing as it's uncertain we'll ever merge this