bson: support all non-deprecated types and fix int/uint bugs

[matthewdale]

• Add support for reading javascript elements.
• Add support for reading decimal128 elements (only printing as binary for now, with a TODO to parse the decimal128 value).
• Add support for reading minkey and maxkey elements
• Fix BSON document length: read int32 instead of uint32.
• Fix binary element size: read int32 instead of uint32.
• Fix datetime: read int64 instead of int32.
• Update BSON test file to include at least one field for every supported type.

[wader]

👍 Nice, will review later this evening

[wader]

🥳

[wader]

I think it makes sense to add the generate program to a file under format/bson/testdata. Some reason it has to go thru base64 btw?

[wader]

Also thanks for good tests

[matthewdale]

Yeah, I can add the source for the Go program used to generate the test BSON document in format/bson/testdata. There's no reason it needs to use base64, it was just a reliable way to copy binary data from a web browser into a terminal.

[wader]

Aha makes sense

[wader]

Looks good 👍 just some minor things about docs and tests

[wader]

Will merge once CI is green. Thanks a lot!

[wader]

Fails on testing fq -h bson, help(bson)/help("bson") output:

--- FAIL: TestFormats (0.40s)
    --- FAIL: TestFormats/bson/testdata/help_bson.fqtest (0.03s)
        fqtest.go:15: 
            --- expected
            +++ actual
            @@ -8,6 +8,10 @@
               $ fq -d bson . file
               # Decode value as bson
               ... | bson
            +
            +Limitations:
            +
            +- The decimal1[28](https://github.com/wader/fq/actions/runs/4848437587/jobs/8641291596?pr=650#step:5:29) type is not supported for decoding, will just be treated as binary
             
             Convert represented value to JSON
             =================================
FAIL

Sorry I forgot in the review that bson.md should use markdown 3-level sections so change Limitations: to ### Limitations.
After that run WRITE_ACTUAL=1 go test -run TestFormats/bson ./format and will rewrite the test output.

To be clear the markdown in bson.md is used both for formats.md and in the builtin help system where it's rendered a bit differently to be CLI friendly. Have some vague plan of using them to generate man pages etc also.

BTW if you want you can also add authors section, something like:

### Authors
- Mattias Wadman mattias.wadman@gmail.com, original author
- Matt Dale <contact info if you like>, additional types and bug fixes 

[matthewdale]

@wader Thanks for the feedback and recommendations! I think I've made all the changes and fixes you suggested.

[wader]

@matthewdale 🥳 Thanks and let me know if you have any question about the other improvements we talking about, happy to help out!