Keybindings config flag

Description

This PR introduces a new feature that allows users to configure the keybindings of the TUI through the .dblab.yaml file.

A new flag --keybindings (or -k) has been added to the CLI. When this flag is used, the application will load the keybindings from the configuration file.

The README.md and docs/usage.md files have been updated to document this new feature.

The purpose of this change is to separate the connection config from the key bindings, so that, the user does not have to relay on the --config flag every time new keybindings values needs to be used.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

1. Run make run to start the application with the custom keybindings.
2. Verify that the keybindings from the .dblab.yaml file are being used.
3. Run go test ./... to run the test suite.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have checked my code and corrected any misspellings