feat(prompt-lab): improvements to the prompt lab application

[ludwiktrammer]

• fix(prompt-lab): better error handling in the Prompt Lab app #42
• feat(prompt-lab): configuring LLM in Prompt Lab should be optional #45
• feat(prompt-lab): users should be able to choose and configure LLM from the Prompt Lab app interface #44
• feat(prompt-lab): Installing the ragbits-dev-kit package should automatically register the CLI command #46
• feat(prompt-discovery): prompt discovery should be able to scan any number of arbitrary Python files based on the given file-path pattern #40
• fix(prompt-discovery): prompt discovery should identify prompts based on specific classes, not their names #41
• fix(prompt-lab,prompt-discovery): Prompt Lab app shouldn't crash when encountering prompts without input model #43

[mhordynski]

Installing the ragbits-dev-kit package should automatically register the CLI command in the Python environment (similarly to how this works in db-ally)

Regarding this take a look on #22