Add Teradata FORMAT Clause Parsing

[readjfb]

feat(teradata): parse column format syntax
Support Teradata FORMAT column syntax

• This PR adds parsing support and tests for the rarely used FORMAT clause in Teradata.
• It overloads the _parse_function class in the Teradata dialect to add support for this, and adds a new FormatColumn expression
• Adds new formatcolumn_sql method to sqlglot/expressions.py to recreate the column
• Adds very basic testing for the FORMAT clause

My original Issue: #5325

Link to Associated Teradata Documentation

[readjfb]

Can't figure out why this is failing - running make style and pre-commit run --all-files on my local machine is passing all tests.

[georgesittas]

Perhaps try nuking & recreating your venv, make install-dev and then make style?

[georgesittas]

Thanks for the PR! Can you test a few more things? E.g., do things like this work?

SELECT ('a' || 'b') (FORMAT '...')

Basically, see if a complex expression before (FORMAT ...) is valid syntax.

[georgesittas]

Nit: let's rename this to FormatPhrase. This applies to other things besides columns, right? E.g.:

-- (FORMAT ...) is applied to a SUM expression here
SELECT SUM(Salary) (FORMAT '$$99,999.99') FROM Employee;

[georgesittas]

Suggested change

	if self._match(TokenType.L_PAREN, advance=False):
	index = self._index
	self._match(TokenType.L_PAREN)
	if self._match(TokenType.FORMAT):
	if self._match_pair(TokenType.L_PAREN, TokenType.FORMAT):

[georgesittas]

I'll take this to the finish line, seems like a small lift. Thanks for the PR!

[readjfb]

Thanks for picking this up and closing out! Will look to continue contributing in the future