Tests, continuous integration, new config, other improvements

[darrenburns]

• Sort children in the collection tree to ensure requests appear in the same order each time, regardless of platform.
• Add help text for the headers table.
• Ensure .posting.yaml files are read and written as utf-8 only.
• Add snapshot tests and code coverage reporting.
• Add GitHub Actions on main merge and pull request pushes.
• Add code coverage commenting on pull requests.
• Add configuration for hiding some parts of the UI.
  • heading.show_version (bool, default true) - hide/show version number at top of app.
  • response.show_size_and_time (bool, default true) - hide/show the response content size and time elapsed for the response to arrive from the server in the response area subtitle.
  • text_input.blinking_cursor (bool, default true) - enable/disable the blinking cursor affect across all inputs in the app (excluding the command palette).
• Vendors pytest-textual-snapshot inside Posting to make customisations.
• Add docstrings to snapshot test report.
• Update snapshot test report to a new dark theme.
• Add ability to pass an App instance into snap_compare pytest fixture.

[github-actions[bot]]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
src/posting
__main__.py					60
app.py
collection.py
config.py					152
src/posting/widgets
input.py
text_area.py					302
variable_autocomplete.py
variable_input.py
src/posting/widgets/collection
new_request_modal.py
src/posting/widgets/request
header_editor.py
request_auth.py					135-152
url_bar.py
src/posting/widgets/response
response_area.py					116
Project Total

This report was generated by python-coverage-comment-action