Disable all commands for change if connection is readonly

[chrjorgensen]

Changes

This PR will disable all commands used for changing content on the server, if the connection is marked readonly.
This include terminals and run of actions, but not library list change command or action management etc.

EDIT: C4i will now ask for reload when the readonly value changes in the config.

EDIT: The readonly field has been moved to the Features section as the first option:

EDIT: The readonly connection setting is decribed in the PR #71 in the Docs repo.

EDIT: Save As will now fail with filesystem error if the connection is in readonly mode.

How to test this PR

1. Open a connection marked as readonly
2. No commands for changing server content should not be available and greyed out in the context menus
3. Change the connection config, unmark readonly and reconnect.
4. The commands for changing server content should now be available as usual.

Checklist

• have tested my change
• updated relevant documentation

[worksofliam]

Only one issue I found:

The deploy command still works even in readonly mode (should be a simple package.json addition)

Once that's done, I think we can merge.

Great work!

[worksofliam]

@chrjorgensen I saw you mentioned you're on holiday - let me take over this PR for you.

[worksofliam]

@sebjulliand I've added one small commit to this PR. Any chance you can have a review?