Now the records look like this:

```
{
  "message": "instance is starting",
  "severity": "low",
  "time": "2023-11-22T22:10:24.211+0300",
  "title": "local_startup"
}
{
  "message": "target grade of instance `i1` changed to Online(7)",
  "severity": "low",
  "time": "2023-11-22T22:10:24.334+0300",
  "title": "change_target_grade"
}
{
  "message": "current grade of instance `i1` changed to Replicated(7)",
  "severity": "medium",
  "time": "2023-11-22T22:10:24.436+0300",
  "title": "change_current_grade"
}
```

This patch changes the way audit records are formatted. Previously
we would format them as plain strings (we still do that in tlog),
now we use json to store all KV pairs including the message.

TODO: optimize string allocations using a stream formatter.

Example:

```
{
  "time": "2023-11-16T22:48:08.297+0300",
  "level": "WARN",
  "auth_type": "chap-sha1",
  "message": "created user `idris`",
  "title": "create_user",
  "pid": 66625,
  "cord_name": "main",
  "fiber_id": 111,
  "fiber_name": "raft_main_loop",
  "file": "src/storage.rs",
  "line": 2633
}
```

Dmitry Ivanov authored 1 year ago and Yaroslav Dynnikov committed 1 year ago

Implemented:

- features:
    * FFI wrappers for `say.{h,c}`
    * safe logger object on top of FFI definitions
    * unified tlog/audit definitions for formatting
    * fixed a needless allocation in tlog (new root per each line)

- events:
    * create_user
    * drop_user
    * create_role
    * drop_role
    * change_password
    * grant_privilege
    * revoke_privilege
    * create_table
    * drop_table
    * grant_role
    * revoke_role

Todo:

- features:
    * unique id generation
    * security subject (who executed the action)
    * audit configuration (via `pico.audit` function)

- well-defined events:
    * create_database (universe)
    * change_config
    * change_current_grade

- special events (local to each node):
    * auth_ok / auth_fail
    * access_denied (still not sure if we absolutely need that)
    * audit_rotate

- Unavailable (haven't been defined yet):
    * rename_user
    * create_procedure
    * drop_procedure

Example:

```
$ cat /tmp/audit.log
2023-11-10 12:07:19.457 [15735] main/103/interactive I> audit log is ready, title: initialize_audit
2023-11-10 12:07:19.457 [15735] main/103/interactive I> database is starting, title: startup
2023-11-10 12:07:19.818 [15741] main/103/interactive I> audit log is ready, title: initialize_audit
2023-11-10 12:07:19.818 [15741] main/103/interactive I> database is starting, title: startup
2023-11-10 12:07:34.910 [15741] main/111/raft_main_loop storage.rs:2809 W> created user `KEK`, auth_type: chap-sha1, title: create_user
2023-11-10 12:07:52.869 [15741] main/111/raft_main_loop storage.rs:2861 W> created role `mgr`, title: create_role
2023-11-10 12:07:55.602 [15741] main/111/raft_main_loop storage.rs:2861 W> created role `kek`, title: create_role
2023-11-10 12:07:57.594 [15741] main/111/raft_main_loop storage.rs:2906 W> granted role `mgr` to role `kek`, title: grant_role
2023-11-10 12:08:08.482 [15741] main/111/raft_main_loop storage.rs:2913 W> granted privilege execute on universe `` to role `kek`, title: grant_privilege
```

To highlight all the logging messages containing the given key do this:
* rust: `tlog::highlight_key(log_key, Some(color))`.
* lua: `picolib.log.highlight_key(log_key, color)`.

To disable highlight for the given key do this:
* rust: `tlog::highlight_key(log_key, None)`.
* lua: `picolib.log.highlight_key(log_key)`.

To disable highlighting of all keys do this:
* rust: `tlog::clear_highlight()`.
* lua: `picolib.log.clear_highlight()`.

+ tarantool-sys submodule
+ tarantool-patches directory
+ build.rs build script to patch and build tarantool
+ static linking with tarantool
+ refactoring for cli arguments

Move tarantool+slog related stuff to a separate module `tlog`.
Introduce the `tlog!` macro for easier logging.