feat(DBI): fill in more DBI internals used by test suite

[fglock]

Summary

Phase 3 first batch of the DBI test-parity plan. Adds the methods the DBI self-tests and the bundled pure-Perl DBDs (DBD::File, DBD::DBM, DBD::Sponge, DBD::Mem, DBI::DBD::SqlEngine) call on DBI and on handles. Nothing architecturally new — it's all straight ports of existing real-DBI logic into the Perl-side glue we started in #544.

What's added

Top-level DBI methods / helpers:

• DBI->internal (fake DBD::Switch::dr drh that isa('DBI::dr'))
• DBI->parse_dsn
• DBI->driver_prefix (accepts both 'File' and 'DBD::File')
• DBI->dbixs_revision
• DBI->install_method / DBI->_install_method
• DBI::hash (ported from DBI::PurePerl)
• DBI::_concat_hash_sorted
• DBI::dbi_profile / dbi_profile_merge / dbi_profile_merge_nodes
• DBI->data_sources now also accepts the "dbi:DRIVER:" form.

Trace fix in DBI.pm: DBI->trace / DBI->trace_msg now work as class methods (previously crashed on strict refs when the invocant was "DBI").

DBD::_::db base class: do, prepare_cached, selectrow_array / _arrayref / _hashref, selectall_arrayref / _hashref, selectcol_arrayref, type_info stub.

DBD::_::st base class: fetchall_arrayref (plain / slice / hash), fetchall_hashref, _get_fbav, and a FETCH override computing NAME_lc / NAME_uc / NAME_hash / NAME_lc_hash / NAME_uc_hash from NAME when called via $sth->FETCH(...). Direct $sth->{NAME_lc} access still requires tied-hash semantics, which we don't provide.

DBD::_::common base class: FETCH_many, debug, dbixs_revision, install_method, dump_handle.

Effect on jcpan -t DBI (stacked on #544)

	Files	Subtests	Passing	Failing
before	200	1600	1240	360
after	200	5610	3978	1632

+2738 subtests now pass (+4010 more executed). 4 fewer test files fail overall. The remaining 166 files are dominated by (a) DBD::File / DBD::DBM-specific methods not yet wired and (b) tied-hash-dependent attribute access.

Cumulative across stacked PRs

	Subtests	Passing
master	562	308
+ #540 (Exporter)	638	368
+ #542 (verify fallback)	946	676
+ #544 (install_driver)	1600	1240
+ this PR	5610	3978

~13× more subtests passing than master.

Depends on

• feat(DBI): driver-architecture + pure-Perl DBD support #544 (pure-Perl DBD support) — this PR is based off that branch. Also transitively depends on fix(backend): interpreter fallback on runtime VerifyError #542 and fix(DBI): wire Exporter + :sql_types/:sql_cursor_types/:utils tags #540.

Test plan

• make (full unit tests) passes.
• ./jperl ~/.cpan/build/DBI-1.647-5/t/01basics.t runs 94+ subtests (was 78).
• ./jperl ~/.cpan/build/DBI-1.647-5/t/02dbidrv.t runs 54 subtests (was 37).
• ./jperl ~/.cpan/build/DBI-1.647-5/t/48dbi_dbd_sqlengine.t runs 22 subtests with 21 passing.
• jcpan -t DBI baseline matches the table above.

Generated with Devin

[fglock]

Superseded by unified PR (see new PR). All four commits rebased into a single branch targeting master.