Incomplete PRAGMA support

I have noticed some inconsistencies in the handling for SQLite pragmas.

1. There is a setter for busy_timeout= but no getter. Likewise for ignore_check_constraints=.
2. No accessors for analysis_limit hard_heap_limit trusted_schema
3. No method for optimize
4. No methods for function_list module_list pragma_list
5. No methods for table_list table_xinfo

For the last, SQLite supports 3 pragmas for index and table:

• thing_list
• thing_info
• thing_xinfo

The gem I have installed, version 2.0.4, has methods for all three index pragmas but only the table_info method.

Some of these may not make sense to support, but these are my findings. Separately, I have some ideas about how to reorganize lib/sqlite3/pragmas.rb.

Review lib/sqlite3/pragmas.rb and compare the existing index and table pragma methods with the requested SQLite pragmas. Decide which missing accessors and methods are appropriate to support, then verify that each selected pragma is exposed consistently; the issue is complete when the chosen support is implemented.