Clean up INFORMATION_SCHEMA.INNODB_ tables

Let us clean up several inconsistencies and inefficiencies in the INFORMATION_SCHEMA table plugins of InnoDB:

• For Boolean attributes, use INT(1) NOT NULL instead of VARCHAR containing strings like 'NO','YES','disabled','enabled','Uninitialized','Initialized'.
• For 32-bit integer attributes, use INT instead of BIGINT.
• For n-ary attributes, use ENUM instead of VARCHAR.
• Remove the unnecessary column SYS_TABLESPACES.SPACE_TYPE.
• Shorten many string columns to more reasonable length. Index and column names can be up to NAME_CHAR_LEN (64) characters long.

Also, implement some functional changes, such as reducing the memory usage for i_s_locks_row_t and i_s_trx_row_t, and replacing some function calls with inlined code.