Miniwdl

* In scatters, embed a string representation of the scatter variable in each call's logs and run subdirectory structure.
* Facilitates identification of the call processing a given sample, but the string tag must be derived heuristically.
* The tag length can be adjusted by config `[scheduler] scatter_max_tag` (0 to disable the new tagging).
* Add config `[file_io] use_relative_output_paths = true` to flatten the `out/` links structure. (606 rhpvorderman)
* The generated link path relative to `out/` reflects the path relative to the original task working directory.
* Fails in the event of an output link path collision (e.g. a workflow outputting files with colliding names generated by different calls).
* Fix `out/` link directory structure for Maps (where subfolders used numeric indexes even if the map keys were suitable path components).
* Fix postprocessing absent `File?`/`Directory?` task outputs. (614 rhpvorderman)
* Fix parsing string literals ending with escaped backslash, e.g. `"foo\\"`.
* `miniwdl zip`: Fix archival of local WDL that imports a remote URI. (610 yunhailuo)

**WDL `version development` features (experimental & subject to change)**

* https://github.com/openwdl/wdl/pull/414 Multi-line strings: the `<<< >>>` task command delimiters can now be used to write multi-line string literals wherever needed.
* https://github.com/openwdl/wdl/pull/504 Support Defining Environment Variables Within a Task: task input declarations can be prefixed by the keyword `env` to bind the input as an environment variable for the command (an alternative to WDL command interpolations/placeholders).

* `miniwdl run`: adapt to [importlib_metadata v5.0.0](https://github.com/python/importlib_metadata/blob/main/CHANGES.rst#v500) removing certain API methods
* Fixes `AttributeError: 'EntryPoints' object has no attribute 'get'` on startup
* To keep using an older miniwdl version, `pip3 install importlib_metadata~=4.0`
* `miniwdl check`: warning for certain string coercions that will become invalid in a future miniwdl version (596)
* `miniwdl zip`: handle imports with single-quoted URIs (601 cvaske-clear)

* Directory localization from Google Cloud Storage (`gs://.../`) (578 cvaske)
* Config option `[file_io] allow_any_input = true` (env `MINIWDL__FILE_IO__ALLOW_ANY_INPUT=true`) allows workflows to read any file/directory on the host filesystem, instead of (default) only paths the operator expressly specified as workflow inputs.
* **(Security / Potentially Breaking)** closes a few cases in which this access check was previously omitted, such as a workflow outputting a specific host path without calling any task on it. Thus, some workflows that previously ran on default settings may now need this option to be set (or, preferably, refactored to explicate their inputs).
* Singularity backend: optionally cache *.sif image files in a local directory (579 rhpvorderman)
* Fix several bugs, and improve error messages, related to reading arrays of nested structs from JSON inputs or `read_json()` (580)
* Fix potential deadlocks with scattered/nested subworkflow calls (591)

* Internal improvements to plugin API for adding container backends, which is now better-documented through [miniwdl-backend-example](https://github.com/miniwdl-ext/miniwdl-backend-example)
* `miniwdl check`: new UnexpectedRuntimeValue flags unexpected types in task runtime{} entries
* `miniwdl run` no longer creates `.WDL_File` dotfiles under the `out/` subdirectory. Directory outputs are still marked by `.WDL_Directory` dotfiles alongside, which suffice to distinguish them from subdirectories corresponding to compound types.

* prevent deadlocks arising from deeply-nested subworkflow calls (573 jrandall)
* use bash login shell (`-l`) in podman/singularity/udocker backends
* add configuration option `[file_io] mount_tmpdir` to optionally control TMPDIR in task environments
* fix `out/` links to cached URIs

* Run task command in login shell (569 nh13)
* Fix failure to recognize string interpolation preceded by `>` (571 Hua-clearlabs)
* `out/` links include local copies of URI outputs (566)
* sort output JSON keys