sqlite3: improve scoping of functions in the sqlite3 extension module

[erlend-aasland]

Clean up scoping/namespace by moving some functions. This will also help future refactoring I've got planned.

• pysqlite_step(): gh-92206: Improve scoping of sqlite3 statement step helper #92207
  Defined in: Modules/_sqlite/util.c
  Used only in: Modules/_sqlite/cursor.c

• bind params helpers: gh-92206: Improve scoping of sqlite3 bind param functions #92250
  Defined in: Modules/_sqlite/statement.c
  Used only in: Modules/_sqlite/cursor.c

• pysqlite_connection_register_cursor(): gh-92206: Improve scoping of sqlite3 register cursor helper #92212
  Defined in: Modules/_sqlite/connection.c
  Used only in: Modules/_sqlite/cursor.c

• pysqlite_statement_reset(): gh-92206: Improve scoping of sqlite3 reset statement helper #92241
  Defined in: Modules/_sqlite/statement.c
  Used only in: Modules/_sqlite/cursor.c

• pysqlite_statement_mark_dirty(): gh-92206: Improve scoping of sqlite3 taint statement helper #92260
  Defined in: Modules/_sqlite/statement.c
  Used only in: Modules/_sqlite/cursor.c

[erlend-aasland]

Thanks for helping, Jelle!