Example Dylint libraries

The example libraries are separated into the following three categories:

general - significant concerns; may produce false positives
supplementary - lesser concerns, but with a low false positive rate
restriction - lesser or stylistic concerns; may produce false positives (similar to Clippy's "restriction" category)
experimental - not ready for primetime yet (similar to Clippy's "nursery" category)
testing - used only for testing purposes

General

Example	Description/check
`abs_home_path`	String literals that are absolute paths into the user's home directory
`await_holding_span_guard`	Span guards held while calling await inside an async function
`basic_dead_store`	A lint to find simple instances of dead stores in arrays
`crate_wide_allow`	`#![allow(...)]` used at the crate level
`incorrect_matches_operation`	Incorrect operators used with matches! macros
`non_local_effect_before_error_return`	Non-local effects before return of an error
`non_thread_safe_call_in_test`	Non-thread-safe function calls in tests
`wrong_serialize_struct_arg`	Calls to `serialize_struct` with incorrect `len` arguments

Example	Description/check
`commented_code`	Code that has been commented out
`escaping_doc_link`	Doc comment links that escape their packages
`local_ref_cell`	`RefCell` local variables
`redundant_reference`	Reference fields used only to read one copyable subfield
`unnamed_constant`	Unnamed constants, aka magic numbers
`unnecessary_borrow_mut`	Calls to `RefCell::borrow_mut` that could be `RefCell::borrow`
`unnecessary_conversion_for_trait`	Unnecessary trait-behavior-preserving calls

Example	Description/check
`assert_eq_arg_misordering`	`assert_eq!(actual, expected)`
`collapsible_unwrap`	An `unwrap` that could be combined with an `expect` or `unwrap` using `and_then`
`const_path_join`	Joining of constant path components
`env_literal`	Environment variables referred to with string literals
`inconsistent_qualification`	Inconsistent qualification of module items
`misleading_variable_name`	Variables whose names suggest they have types other than the ones they have
`overscoped_allow`	`allow` attributes whose scope could be reduced
`question_mark_in_expression`	The `?` operator in expressions
`ref_aware_redundant_closure_for_method_calls`	A ref-aware fork of `redundant_closure_for_method_calls`
`register_lints_warn`	Calls to `rustc_errors::DiagCtxtHandle::warn` from within a `register_lints` function
`suboptimal_pattern`	Patterns that could perform additional destructuring
`try_io_result`	The `?` operator applied to `std::io::Result`

Example	Description/check
`derive_opportunity`	Traits that could be derived
`missing_doc_comment_openai`	A lint that suggests doc comments using OpenAI

Example	Description/check
`clippy`	All of the Clippy lints as a Dylint library
`marker`	Marker lints run from a Dylint library
`straggler`	A lint that uses an old toolchain for testing purposes

Notes

Each example is in its own workspace so that it can have its own rust-toolchain.
Each example is configured to use the installed copy of dylint-link. To use the copy within this repository, change the example's .cargo/config.toml file as follows:
```
[target.x86_64-unknown-linux-gnu]
linker = "../../../target/debug/dylint-link"
```