[amp-carousel:1.0] Bento tracking issue

## High-level requirements for `amp-base-carousel`
| Consideration | Ready when | Status |
| ------------- | ------------- | ------- |
| Component compatibility | [Conformance with 0.1 (see below)](https://amp.dev/documentation/components/amp-base-carousel/) | ✅ |
| Testing | Unit tests and e2e tests from 0.1 | ✅ |
| Internationalization | RTL supported | ✅ |
| Analytics | `slideChange` supported | ✅ |
| Accessibility | Audit performed, [0.1 for reference](https://github.com/ampproject/amphtml/issues?q=is%3Aissue+is%3Aopen+label%3A%22UI%3A+Component%3A+amp-carousel%22+label%3A%22Related+to%3A+Accessibility%22) |✅ |
| Page experience | Audit performed |✅ |
| Documentation | Written |✅ |
| Storybook | Samples written | ✅ |

### Open tasks

- [x] Initial design and implementation (See #28704 for Preact layer, See #29303 for AMP layer)
- [x] Expose a basic subset of the [documented AMP attributes](https://amp.dev/documentation/components/amp-base-carousel/) as `props` for `BaseCarousel`; existing attributes:
- [x] `loop`
- [x] `controls`
- [x] `mixed-length`
- [x] `visible-count`
- [x] `advance-count`
- [x] `auto-advance`
- [x] `auto-advance-count`
- [x] `auto-advance-interval`
- [x] `auto-advance-loops`
- [x] `snap`
- [x] `snap-align`
- [x] `snap-by`
- [x] `slide`
- [x] `horizontal` -> `orientation`
- [x] Style default arrows similarly to existing ones on `amp-base-carousel`, possibly also [removing `dir`](https://github.com/ampproject/amphtml/pull/28704#discussion_r451800639) (See #29338)
- [x] RTL support
- [x] Resolve in-slide layout (ex. user styled `height: 50%`)
- [x] Use `forwardRef` to [dedup multiple refs](https://github.com/ampproject/amphtml/pull/28704#discussion_r454696809) in `Scroller` and `BaseCarousel` (See #29505, #29650)
- [x] Watch for mutations
- [x] Decide on [boolean=false](https://docs.google.com/document/d/1G_WMXyyKGoHHta6iyXr0dF2B-kLGm_cAoArdVcn0VNg/edit#) attributes
- [x] ~Investigate use of `order` to reorder slides~
- [ ] Position arrows on top/bottom of carousel when `orientation="vertical"` - make sure that this does not cause CLS for `outsetArrows={true}`. [See comment.](https://github.com/ampproject/amphtml/pull/31286#issuecomment-736130609)
- [x] Expose DOM events #32194
- [ ] Expose `actionTrust` or `autoplay` boolean information with event data for `slideChange`

### Migration notes
- `"horizontal"="true"|"false"` in 0.1 is replaced by `"orientation"="horizontal"|"vertical"` in 1.0

## High-level requirements for `amp-inline-gallery`
| Consideration | Ready when | Status |
| ------------- | ------------- | ------- |
| Component compatibility | [Conformance with 0.1 (see below)](https://amp.dev/documentation/components/amp-inline-gallery/) | ✅ |
| Testing | Unit tests | ✅ |
| Internationalization | RTL supported | ✅ |
| Analytics | n/a | n/a |
| Accessibility | Audit performed |✅ |
| Page experience | Audit performed |✅ |
| Documentation | Written |✅ |
| Storybook | Samples written | ✅ |

### Open tasks
- [x] Preact layer (#29674 preferred to #29545)
- [x] Support `Pagination` and optional attribute `inset` (See #29545)
- [x] Support `Thumbnails` and optional attribute `loop`. The following `amp-base-carousel` features must be supported as a prerequisite:
- [x] `snap` and `snapAlign`
- [x] `controls`
- [x] `mixedLength`
- [x] [responsive attributes](https://amp.dev/documentation/components/amp-base-carousel/#using-media-queries)
- [ ] Support `Captions` and `Slide` components

## High-level requirements for `amp-stream-gallery`
| Consideration | Ready when | Status |
| ------------- | ------------- | ------- |
| Component compatibility | n/a (0.1 is experimental) | n/a |
| Testing | Unit tests | ✅ |
| Internationalization | RTL supported | ✅ |
| Analytics | `slideChange` supported | ✅ |
| Accessibility | Audit performed |✅ |
| Page experience | Audit performed |✅ |
| Documentation | Written |✅ |
| Storybook | Samples written | ✅ |

### Open tasks
- [x] Attributes:
- [x] `min-item-width`
- [x] `max-item-width`
- [x] `max-visible-count`
- [x] `inset-arrow-visibility`
- [x] `outset-arrows`
- [x] `loop`
- [x] `snap`
- [x] Watch for mutations

Start by reviewing the remaining unchecked tasks for amp-base-carousel and amp-inline-gallery, especially vertical arrow positioning, slideChange event data, and Captions and Slide support. The issue names no source files or tests, so locate the relevant component entry points and existing unit or end-to-end tests first. Done means the remaining checklist items are implemented and covered by the project’s tests.

Written by the indexing model from the issue text.