Add CollectT.Halt() as a fail-fast helper for EventuallyWithT

[twz123]

Summary

Add CollectT.Halt() so fatal assertions invoked inside EventuallyWithT can stop the retry loop.

Changes

Add the new HaltT struct that acts as a CollectT wrapper. Whenever an error or failure is recorded, the wrapping HaltT will set CollectT's new halt flag, so that the EventuallyWithT loop can detect this and error out early.

Motivation

This allows for cleanly breaking out of the test loop before the timeout has elapsed, if necessary:

condition := func(c *CollectT) {
	require.True(c.Halt(), socketsOpen(), "socket must be open before proceeding")
	assert.True(c, eventuallyTrue(), "non-fatal checks still run until success/timeout")
}
assert.EventuallyWithT(t, condition, time.Second, 10*time.Millisecond)

Related issues

• Improve the behavior of require assertions when using assert.EventuallyWithT #1396
• Handle unexpected exits in condition polling #1819