Config GUI: add new tab for logging

[bpintea]

Currently, the only way to configure the tracing of actions the driver is asked to perform is possible by using environment variables. A more practical (and possibly very useful for pre-releases) way of configuring this is through the DSN, per connection. This would require a new tab to the DSN editor:

• enable/disable logging;
• allow choose a directory where to write the log fileS;
• the log level.

[codebrain]

What shall the default log level be?

At least for alpha I think we should use DEBUG as there is likely to be more to gain with logging more than we might think we need.

We can always bump to WARNING when this stabilises.

[codebrain]

Will send and receive values as strings (case insensitive):

DEBUG
INFO
WARN
ERROR

Does this make sense with

elasticsearch-sql-odbc/driver/log.h

Line 58 in aedca96

enum osodbc_log_levels {

?

[bpintea]

@codebrain I realized that the enabled/disabled setting I was mentioning above has currently no storage in the DSN string. It would be nice to be able to disable the logging though, without having to delete the directory path setting. For that, we could go two ways: add a DISABLED level setting, or add another DSN parameter and a corresponding tick for it.
The former would be easier to accommodate, the latter would be more intuitive. What do you think?

[codebrain]

@bpintea

Easiest would be to add a DISABLED log level, but there is part of me that thinks we ought to do the right thing and have an on/off flag as another DSN parameter.

The reason being we don't know where this logging system might end up and I imagine the likelihood of a on/off flag is better than a DISABLED log level in any other system...

New DSN parameter: TraceEnabled? Set to either 1 or 0?

[bpintea]

@codebrain TraceEnabled sounds good, thanks!

[codebrain]

Implemented in UI as:

The checkbox enables/disables the relevant controls but all underlying values are parsed and sent to/from the driver.

[bpintea]

Looks great, works as expected. Thank you!