Reduce system.name to 128 chars

Problem/Motivation

During our work with chx on #298600: DBTNG: make module_implements work regardless of bootstrap phase → , we stumbled over an issue regarding the length of module, function and hook names.

In a nutshell: currently module names are limited to 255 chars (the length of system.name), but function names are limited to 255 chars. That means that hook names are limited to... -1 chars (because strlen(module_name . '_' . hook_name) <= 255...).

Proposed resolution

So I suggest we settle on:

- modules names limited to 128 chars
- function names limited to 255 chars
- hook names limited to 126 chars

That would mean changing system.name to 128 chars (ie. themes will also be affected, but I don't think this would have any consequences), so also system.owner, and may be some other columns using those.

Remaining tasks

This needs to still be decided upon.

User interface changes

None.

API changes

The naming system would be changed.

Data model changes

None.