go/mcap: do not write empty message indexes (foxglove#873)

### Public-Facing Changes

Go MCAP writer no longer produces message index records for channels not present in a chunk. This helps indexed readers skip chunks that do not contain any messages on a given channel.

### Description
Fixes foxglove#862

go/mcap: do not write empty message indexes (foxglove#873)

### Public-Facing Changes

Go MCAP writer no longer produces message index records for channels not present in a chunk. This helps indexed readers skip chunks that do not contain any messages on a given channel.

### Description
Fixes foxglove#862

typescript: make forward and reverse iterators true opposites with mu…

…ltiple message at same timestamp within a chunk (foxglove#859)

### Public-Facing Changes

TypeScript @mcap/core: fixed an issue where `readMessages({ reverse: true })` and `readMessages({ reverse: false })` would return messages in the same order when multiple messages were at the same timestamp.

### Description

`Array#sort()` is a stable sort. This means if multiple messages have the same timestamp, `sort(([a, b]) => b - a)` and `sort(([a, b]) => a - b)` would keep them in the same order. Instead of changing the comparator, we use `Array#reverse()` in the reverse case.

Note that this fix addresses messages within one chunk. It's possible there is still a similar issue when merging across multiple chunks.

Relates to https://github.com/foxglove/studio/issues/5551 / FG-2498

python/mcap: fix statistics deserialization (foxglove#846)

* python/mcap: fix reading of statistics message channel count

* python/mcap: bump patch version

CLI: info: handle durations > 2**63 (foxglove#844)

* CLI: info: handle durations > 2**63

* make a function

* correct comment

Specify that installing with go install is not supported (foxglove#826)

[TypeScript] @mcap/support (foxglove#838)

[TypeScript] @mcap/support (foxglove#838)

@mcap/core 1.2.0 (foxglove#836)

fix bad mutation in merge (foxglove#839)

**Public-Facing Changes**
Fixed a bug where `mcap merge` would incorrectly change some channels' schemas.
Fixed a bug where `mcap merge` would crash on some input files with schemaless channels (schemaId=0).

**Description**
Fixes foxglove#837