[FEATURE] Enable Users to Customize Email Body Modification

[adityapansare]

Is your feature request related to a problem? Please describe. Email alerts are enabled for each Expectation that is triggered. These emails are not verbose barring a few status indicators (Passed, Skipped, Failed), and output/error percentages. It doesn't offer users the ability to set their own email body, and leverage the statistics, to make it more readable.

Describe the solution you'd like Can we have options where we could pass string/HTML email body with the ability to import the stats/rules as a part of it?

Describe alternatives you've considered None as the platform doesn't often an alternative.