Lifting of the codec packages

[dalex78]

Objective: Lifting of the codec packages:

• Adding comments
• Harmonizing names when applicable
• Documentation
• Add support for 64bits integer (VHDL 2019) (the codec must adapt itself depending on integer'high for example)
• Add functions to calculate the size of the encoded data(i.e. number of bytes) it will take to encode the given array.
• Add functions to retrieve the range of an encoded array. This might be useful for the queue_t package which also push the range of the array I believe. (I need to double check that).

Rational: The codec packages have a lot of hard coded value, few comments and documentation. There are also some inconsistency with the name of some functions like: encode_array_header which should be encode_range and rename get_range into decode_range. When adding the peek functionality (#814), I have found hard to enter into the code.

What has been done:

• Work is under way at: rework_vhdl_data_type
• A list (non-exhaustive) of things that have changed or will be changed: todo/to be done

Remaining work: (if this feature is wanted/accepted by the community)

• Finishing the lifting of the codec package,
• Launch all tests,
• Documentation

Note: This work will most likely be retro-compatible. I'll get back on that topic later.