This PR updates the list of reserved words that cannot be used unquoted as identifiers. The list was generated using a C program that iterates over the full set of keywords in SQLite and attempts to do CREATE TABLE t(<keyword> INTEGER); for each one, tracking which keywords fail. Many words that were previously in the reservedMap passed this test and have been removed.

Removing items from that list prompted a bit of yak shaving:

• The alias_ident rule has been split into alias_ident_explicit (i.e. using AS) and alias_ident_implicit (not using AS, e.g. SELECT * FROM foo bar WHERE bar.val = 1).
• A new invalidImplicitAliasMap is added (generated using the same C program) to track which keywords cannot be used as implicit aliases. There's a lot of overlap with reserveredMap, but there are items exclusive to both lists.
• More joins have been implemented. RIGHT joins were previously incorrectly parsed as aliases because the join_op rule didn't implement them, but now they were broken entirely, so I went ahead and implemented them + other missing joins.
• Added tests for all joins
• The alter_table_stmt rule now only supports one table name (which is correct for SQLite), as the previous rule was not compatible with the alias rule updates. That rule used table_ref_list which supports aliases for table names, which caused the parser to interpret things like RENAME as table aliases. Aliases are not valid in ALTER TABLE statements.