sql: add github issue number to the following unimplemented features

[awoods187]

Describe the problem

Add github issue tracking number to the following unimplemented features:

• unimplemented.alter set type | sql: support ALTER TABLE ... ALTER COLUMN ... SET DATA TYPE ... #9851 with details
• unimplemented.alter set non null | sql: support ALTER TABLE ALTER COLUMN SET NOT NULL #28751
• unimplemented.alter using | sql: support ALTER TABLE ... ALTER COLUMN ... SET DATA TYPE ... #9851 with details
• unimplemented.create sequence OWNED BY option | sql: support create sequence OWNED BY option #26382
• unimplemented.at tz |  sql: Support the "at tz" operator #32005
• unimplemented.on conflict on constraint | sql: support INSERT ... ON CONFLICT ON CONSTRAINT #28161
• unimplemented.match simple | sql: Composite Foreign Key Matching (PARTIAL) #20305
• unimplemented.frame_bound |  Implemented in v2.1 via window function improvements
• unimplemented.func_application |  Implemented in v2.1 via window function improvements
• unimplemented.alter add fk | sql: Support ALTER TABLE __ ADD CONSTRAINT __ FOREIGN KEY __ statements #8855
• unimplemented.with recursive | sql: WITH RECURSIVE (recursive common table expressions) #21085
• unimplemented.alter add computed | Implemented in v2.1
• unimplemented.set local | sql: support SET LOCAL and txn-scoped session variable changes #32562
• unimplemented.index_elem a_expr | sql: support expression-based index columns #9682
• unimplemented.func_expr_common_subexpr | sql: support pg_collation_for() and its COLLATION FOR () syntactic sugar #32563 
• unimplemented.func const | sql: more assorted telemetry fixes #32556 
• unimplemented.create sequence AS option | sql: sequences: support AS <datatype> #25110 with details
• unimplemented.alter add check | sql: enable adding CHECK constraints in ALTER TABLE ADD COLUMN #29639
• unimplemented.alter column type | sql: support ALTER TABLE ... ALTER COLUMN ... SET DATA TYPE ... #9851 with details
• unimplemented.pg_catalog.pg_matviews | N/A
• unimplemented.pg_catalog.pg_statio_user_tables | N/A
• unimplemented.import.mysqlcoltype.GEOMETRY |  importccl: enable importing MySQL SET columns #32560, importccl: enable importing GEOMETRY columns from MySQL #32559 and importccl: enable importing MySQL BIT columns #32561

[knz]

• some of these are already done in 2.1 but maybe should be backported to 2.0
• some of these may not be clearly reproducible or maybe context is missing, in which case we may still want to invite users to submit an issue.