feat: add CapturePanic method

[giortzisg]

Description

This adds a convenience method to capture panics. Panics even as messages should always have an active stacktrace, so this PR also changes the old recover behavior to include stacktraces on captured string literals.

Issues

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[sentry]

Bug: In capturePanic, accessing event.Exception after a call to eventFromException without checking if the slice is empty can cause a panic within the panic handler.
_{Severity: HIGH}

Suggested Fix

Before accessing event.Exception[len(event.Exception)-1] in the error case within capturePanic, add a guard to check that len(event.Exception) > 0. If the slice is empty, the logic should proceed to the existing handling for empty exceptions, which creates a Thread with the stacktrace.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: client.go#L793-L794

Potential issue: In the `capturePanic` function, when handling a panic value of type
`error`, the code calls `client.eventFromException` and then immediately accesses
`event.Exception[len(event.Exception)-1]` to assign a stacktrace. However,
`eventFromException` can return an event with an empty `Exception` slice, for example if
`client.options.MaxErrorDepth` is configured to be 0. If this occurs, the unguarded
slice access will cause an index-out-of-bounds panic. Because this happens inside the
panic handler itself, it will cause an unrecoverable application crash instead of
capturing the original panic.

_{Did we get this right? 👍 / 👎 to inform future reviews.}