DOCS: Added PlayerInput.ActionEvent documentation

[lyndon-unity]

Description

Added PlayerInput.ActionEvent documentation
Updated PlayerInput documentation to improve, adding missing parameters, adding some examples, moving some see also links into the remarks as part of explanations.

Testing status & QA

Reviewed generated docs using the DocTools package and checked the validation results

Overall Product Risks

• Complexity: low
• Halo Effect: low

Comments to reviewers

Checklist

Before review:

• Changelog entry added.
  • Explains the change in Changed, Fixed, Added sections.
  • For API change contains an example snippet and/or migration example.
  • JIRA ticket linked, example (case %%). If it is a private issue, just add the case ID without a link.
  • Jira port for the next release set as "Resolved".
• Tests added/changed, if applicable.
  • Functional tests Area_CanDoX, Area_CanDoX_EvenIfYIsTheCase, Area_WhenIDoX_AndYHappens_ThisIsTheResult.
  • Performance tests.
  • Integration tests.
• Docs for new/changed API's.
  • Xmldoc cross references are set correctly.
  • Added explanation how the API works.
  • Usage code examples added.
  • The manual is updated, if needed.

During merge:

• Commit message for squash-merge is prefixed with one of the list:
  • NEW: ___.
  • FIX: ___.
  • DOCS: ___.
  • CHANGE: ___.
  • RELEASE: 1.1.0-preview.3.

After merge:

• Create forward/backward port if needed. If you are blocked from creating a forward port now please add a task to ISX-1444.

[ekcoh]

I believe null should have formatting here?

[ekcoh]

Should this have ?

[lyndon-unity]

Ill add < c > around the null. I assume these whats meant.

I don't understand the '?' query

[ekcoh]

CI errors on docs formatting it seems

[lyndon-unity]

CI errors on docs formatting it seems

Fixed formatting, addressed a whole load more documentation issues from the low score on the documentation assessment.

[ekcoh]

Are we ok with non-compilable examples? @duckets

[lyndon-unity]

It should compile but not in isolation. I'll await doc writer feedback

[ekcoh]

Similar comment as previously on non-compilable example

[lyndon-unity]

It should compile but not in isolation. I'll await doc writer feedback

[ekcoh]

Still has similar errors in CI as my branch (See dry-run target):

PVP-150-1: UnityEngine.InputSystem.PlayerInput: onActionTriggered: in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: onDeviceLost: in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: onDeviceRegained: in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: onControlsChanged: in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: TDevice GetDevice(): in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: void ActivateInput(): in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: void DeactivateInput(): in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: void SwitchCurrentActionMap(string): in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: PlayerInput GetPlayerByIndex(int): in block context (only allowed in top-level context)
PVP-150-1: UnityEngine.InputSystem.PlayerInput: PlayerInput Instantiate(GameObject, int, string, int, InputDevice): in block context (only allowed in top-level context)
(and 3 more errors)

[lyndon-unity]

Still has similar errors in CI as my branch (See dry-run target):

I've fixed these. Several were already there but I've tided it up.