Support MySQL table option {INDEX | KEY} to the CREATE TABLE, restrict to MySql and generic dialects

[AugustoFKL]

Breaking changes:

• Now HASH and BTREE are KEYWORDS, and using them as names can result in errors.
• Now 'KEY' and 'INDEX' column names start the parsing of a table constraint if unquoted for the Generic dialect. This results in possible conflicts if canonical results are compared for all dialects if a column is named 'key' without quotes.

Theoretically, the behavior should be the same as CREATE INDEX, but we cannot make that assumption, so the parse is (almost) identical to the input. MySQL seems to be the only one to support this syntax. (1)

Now we can support statements like:

CREATE TABLE (id INT, INDEX (id));

CREATE TABLE (id INT, KEY index_name USING BTREE (id))

The supported syntax implemented here is:

CREATE TABLE (..., {KEY | INDEX} [index_name] [USING {BTREE | HASH}] (<key_part>, ...))

<index_name>: Single identifier
<key_part>: Single identifier

[1] : https://dev.mysql.com/doc/refman/8.0/en/create-table.html

[coveralls]

Pull Request Test Coverage Report for Build 3216094339

• 88 of 91 (96.7%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.08%) to 85.866%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/parser.rs	62	63	98.41%
src/ast/ddl.rs	15	17	88.24%

Totals
Change from base Build 3209998484:	0.08%
Covered Lines:	10559
Relevant Lines:	12297

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💛 - Coveralls

[alamb]

Thank you @AugustoFKL

[alamb]

👍