[LLM] Add logs while executing llm command

[kracekumar]

Description

1. Since llm command fetches the schema of the database, creates a prompt and then invokes the llm command with the prompt. add a couple of log lines to indicate to user about the progress.
2. The PR measures entire end to end invocation of the command. The output message is different for run_external_cmd that is directly invoked and invoked via sql_using_llm.
3. I'm happy to modify the messages or colors to make more useful. I have skipped using emojis and sticked with simple useful messages.
4. Example Outputs:

/Users/kracekumar/code/mcp-chatbot/test.db> \llm+ "Show only the top 5 results"
Preparing schema information to feed the llm
Invoking llm command with schema information
Received response from the llm command
LLM Reponse:
...
Explanation:

- We join `people`, `groups`, and `contact_groups` tables to get the required data.
- We use a window function (`ROW_NUMBER()`) to assign a unique number to each person based on their contact_id and group_id. This allows us to sort the results in descending order of these fields.
- The outer query then selects only the top 5 people by filtering `row_num` to be less than or equal to 5.

...

Explanation:

- This query simply counts the number of groups in the database, which represents the total number of people in contact groups.

---
Time: 6.07 seconds
....
/Users/kracekumar/code/mcp-chatbot/test.db> \llm+ -m codellama -c "Show only the top 5 results"
Calling llm command
LLM Reponse:
...
Explanation:

- We join `people`, `groups`, and `contact_groups` tables to get the required data.
- We use a window function (`ROW_NUMBER()`) to assign a unique number to each person based on their contact_id and group_id. This allows us to sort the results in descending order of these fields.
- The outer query then selects only the top 5 people by filtering `row_num` to be less than or equal to 5.
...

Explanation:

- This query simply counts the number of groups in the database, which represents the total number of people in contact groups.

---
Time: 15.61 seconds

Checklist

• I've added this contribution to the CHANGELOG.md file.

[amjith]

Hah. That's clever. I typically do assert duration > 0.0 but this works too. :)

[amjith]

Nicely done. 🚀