Reduce "command returned too much output" errors in email plugin by truncating output

[sdelgadoc]

Motivation:
As a continuation to the discussion with @riensen in PR #177, this PR was created as a way to further reduce "command returned too much output" errors in the email plugin by truncating email output based on configuration settings.

Changes:
Added truncate_emails function that truncates the email plugin's output based on the following requirements discussed in PR #177.

We set three sensible limits:
MAX_CHARACTERS: The maximum number of characters for all emails retrieved
MAX_NUM_EMAILS: The maximum number of emails
MAX_EMAIL_CHARACTERS: The maximum length per body of each email

If MAX_CHARACTERS is breached, then we check how many emails are retrieved and set a return a smaller list
If the MAX_CHARACTERS is breached while MAX_NUM_EMAILS is not breched, then we start truncating each email which exceeds MAX_EMAIL_CHARACTERS starting with the longest one.
We also need to indicate that emails were truncated to Auto-GPT like adding

Testing:
Added test to validate email truncation functionality

Future Work
Consider whether to use ChatGPT API to summarize emails instead of truncating them.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (808016e) 58.52% compared to head (931553e) 58.52%.

Additional details and impacted files

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  Coverage   58.52%   58.52%           
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  Files          36       36           
  Lines        2122     2122           
  Branches      222      222           
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  Misses        858      858           
  Partials       22       22           

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[riensen]

This warning message also takes up token space. We should make it very concise e.g.:
[... Email truncated]

[riensen]

We should also write some unit tests that test the various settings e.g. max_num_emails:

Here some suggestions

    @patch('os.getenv', return_value='1000')
    def test_empty_list(self, mock_getenv):
        truncator = EmailTruncator()
        messages = []
        self.assertEqual(truncator.truncate_emails(messages), [])
    
    @patch('os.getenv')
    def test_max_characters_breached(self, mock_getenv):
        truncator = EmailTruncator()
        mock_getenv.side_effect = ['10', '10', '100']
        messages = [{"Message Body": "Hello world!"}]
        truncated_messages = truncator.truncate_emails(messages)
        self.assertTrue(len(str(truncated_messages)) <= 10)
    
    @patch('os.getenv')
    def test_max_num_emails_breached(self, mock_getenv):
        truncator = EmailTruncator()
        mock_getenv.side_effect = ['1000', '1', '100']
        messages = [{"Message Body": "Hello world!"}, {"Message Body": "Goodbye world!"}]
        truncated_messages = truncator.truncate_emails(messages)
        self.assertEqual(len(truncated_messages), 1)
    
    @patch('os.getenv')
    def test_max_email_characters_breached(self, mock_getenv):
        truncator = EmailTruncator()
        mock_getenv.side_effect = ['1000', '10', '10']
        messages = [{"Message Body": "Hello world!"}]
        truncated_messages = truncator.truncate_emails(messages)
        self.assertTrue(len(str(truncated_messages[0]["Message Body"])) <= 10)

[riensen]

You should also add a test, when these env vars are not set. In this case we must use default values.

[NeonN3mesis]

Sorry I got assigned to this repo. Is this ready to go?

[sdelgadoc]

It is from my point of view, but I believe @riensen want additional tests added.