Smol+async global executor 1.80 dev (#3791)

* Sqlx-core: rename async_io dependency for async-std

* Sqlx-core: simplify TimeoutError

* Sqlx-core: code for async-global-executor

* Sqlx: integrate async-global-executor feature

* Note to unsafe

* Step up MSRV as async-global-executor needs it

* Sqlx-core: fix of unix socket build

* Unsafe fixes, smol executor added

* Workflow fix

* Changes outside sqlx_rt

* Cleanup conditional rt compilation

* Warning

* Add executors to test matrix

* Fix of skipping code sqlite due to mismatch in cargo feature names

* Smol executor isolated

* Fix, reduce number of tests, remove async_std

* Fix of test_block_on, regression

* Format fixes

* async-global-executor added

* async-std changed to 1.13

* litemap, zerofrom requires rustc 1.81

* Fix of missing _sqlite in cargo.toml

* Clippy lints

* Clean up

* Remove features combinations

* Fixes after merge

* Fix of compiling connect_tcp_address with both tokio + other executor selected

* Try to fix CI -Z minimal-versions check

Try to fix CI -Z minimal-versions check