Add dump load dumps and loads to top level asdf

[braingram]

Description

Add a few functions to asdf to mimic the interface used for other serialization libraries (json, pickle, yaml...):

• asdf.dump: Write the provided tree to the provided file path (or file-like object)
• asdf.load: Load the ASDF tree from the provided file path (or file-like object)
• asdf.dumps: Dump to a string
• asdf.loads: Load from a string

I did some minor test reorganization to make testing these new functions a bit easier by moving the tree fixture out of test_generic_io and adding a recursive_tree fixture (this expanded a few tests in test_generic_io).

One plan for these new functions is to use them during an upcoming test reorganization.

These functions should feel familiar to anyone who uses the python json, pickle and/or yaml libraries and should also be useful for some downstream libraries to simplify some asdf uses. For example, roman_datamodels contains the following code:

        af = asdf.AsdfFile()
        af.tree = {"roman": node}
        af.write_to(filepath, all_array_compression="lz4")

This can be simplified to:

        asdf.dump({"roman": node}, filepath, all_array_compression="lz4")

Closes #1873

The docstrings are largely copies of AsdfFile.__init__ asdf.open and AsdfFile.write_to options with some LLM peppered suggestions (which used those docstrings as context).

Tasks

• run pre-commit on your machine
• run pytest on your machine
• Does this PR add new features and / or change user-facing code / API? (if not, label with no-changelog-entry-needed)
  • write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see below for change types)
  • update relevant docstrings and / or docs/ page
  • for any new features, add unit tests

news fragment change types...

• changes/<PR#>.feature.rst: new feature
• changes/<PR#>.bugfix.rst: bug fix
• changes/<PR#>.doc.rst: documentation change
• changes/<PR#>.removal.rst: deprecation or removal of public API
• changes/<PR#>.general.rst: infrastructure or miscellaneous change

[zacharyburnett]

was going to suggest pretty-printing options, but then I realized that we aren't minifying ASDF so it's ALWAYS pretty-printed 😅

[braingram]

was going to suggest pretty-printing options, but then I realized that we aren't minifying ASDF so it's ALWAYS pretty-printed 😅

"mASDF" :)