chore: reorder inputs into logical groups

[madisp]

Reorders the action inputs along the lines we have them in ew-cli and the emulator-wtf/invoke action.

Also added missing forwarding for shard-target-runtime and flaky-test-repeat-mode.

[Copilot]

Pull Request Overview

Reorders inputs in action.yml into logical groups and updates README to reflect the new grouping. Adds missing forwarding for shard-target-runtime and flaky-test-repeat-mode in the composite action.

• Input groups reorganized (authentication, file options, test configuration, sharding, outputs, network, operation)
• Added new forwards for shard-target-runtime and flaky-test-repeat-mode
• README table updated to match reordered inputs (with some inconsistencies)

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
action.yml	Reorganized inputs and added missing forwards for shard-target-runtime and flaky-test-repeat-mode
README.md	Updated input documentation to match new grouping and added descriptions for newly surfaced inputs

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