Enable CREATE TABLE AS GUESS SCHEMA [...] in MML

[curlette]

When running %mml GUESS SCHEMA FOR <table>, the pandas rendering of the resulting table does not display the full strings in the reason column. Thus, it would be helpful to be able to create a table from the output of GUESS SCHEMA FOR <table> in order to select reasons.

This is especially relevant as the --reasons flag in %mml .guess_schema <table> is effectively deprecated due to readability issues: probcomp/iventure#56

[fsaad]

Will required changing the grammar to treat GUESS SCHEMA from a command to a query.