PT-2368 - full refactor of a config library

[BON4]

Rewrite config library to comply with Percona Toolkit specification

Summary

Complete rewrite of the config library to fully comply with the Percona Toolkit configuration file specification. The previous implementation was a simple key-value parser that didn't support many required features.

New Implementation

• Full Percona Toolkit specification compliance

• Integration with kong CLI parser - configs and command-line args work together

• --config flag support - must be first argument, space-separated

• Passthrough arguments - everything after -- passed to mysql/mysqladmin

• no- prefix handling - no-optimize sets optimize=false

• Proper config file precedence - system - user - tool-specific

• Custom types - BoolYN (yes/no/1/0/on/off), StdinRequestString (password prompting)

• Error handling

• Full test coverage

• The contributed code is licensed under GPL v2.0

• Contributor Licence Agreement (CLA) is signed

• util/update-modules has been ran

• Documentation updated

• Test suite update

[svetasmirnova]

Options in the only modified tool do not work as expected:

sveta@s76:~/src/percona/percona-toolkit$ ./bin/pt-k8s-debug-collector --version
pt-k8s-debug-collector: error: couldn't find binding of type []interface {} for parameter 0 of func(...interface {}) error(), use kong.Bind([]interface {})
sveta@s76:~/src/percona/percona-toolkit$ ./bin/pt-k8s-debug-collector version
pt-k8s-debug-collector: error: unexpected argument version

Expected behavior:

$ ./bin/pt-mongodb-summary --version
pt-mongodb-summary
Version 3.7.1
Build: 2026-01-30T15:30:33+0300 using go1.25.5
Commit: 14324ff374b078089e3bbae2bdcf6e09f7c4cc35

And we should not change this format, because it is aligned with other tools.

[svetasmirnova]

See comment above.

[BON4]

@svetasmirnova Yep, forget to push some fixes.

[BON4]

@JiriCtvrtka Not sure if we should change old_config.go because this is old implementation and eventually it will be replaced with the new one. I left it just to support compatibility with not yet migrated tools.

[svetasmirnova]

Please also merge changes from 3.x, so library files have a copyright header, and add a copyright header to the new config.go

[svetasmirnova]

Please answer questions and process suggested changes.