feat: Re-optimize alphabet for Brotli (only chars unused by gzip backrefs)

[subzey]

A follow-up for #309: Although the Brotli size is currently not counted, probably this would be nice to have.

The "brotlied" built non-secure nanoid size goes down from 146 bytes to 129.

The gzip sizes are unchanged for all entries.

How does it work

Currently only 'use, andom and rict' are used to utilize the gzip backrefs. Other chars are just sorted alphabetically (they cannot form a gzip backref so their order is not significant for gzip).

But we also have brotli! And brotli has a built-in the default dictionary. All we need is to rerrange those "other chars" to form some substrings from the dictionary.

After a day running an ad-hoc script gave the answer for the Ultimate Question of Life, the Universe, and Everything this bizarre Scrabble game:

-26T
1983
40px (uppercased)
75px
bush (uppercased)
jack (uppercased)
mind (uppercased)
very (uppercased)
wolf (uppercased)

That forms a "phrase" -26T198340PX75pxJACKVERYMINDBUSHWOLF

Equally good, also producing 129 bytes

-26T139475px80PXBINDGULFJACKVERSWHOM
-26T139475px80PXFINDJOBSMUCHVERYWALK
-26T139475PX80pxBINDGULFJACKVERSWHOM
-26T139475PX80pxFINDJOBSMUCHVERYWALK
-26T198340px75PXBINDGULFJACKVERSWHOM
-26T198340PX75pxBINDGULFJACKVERSWHOM
-26T198340PX75pxBUSHDOWNFILMJACKVERY
-26T198340PX75pxBUSHFILMJACKNDOWVERY
-26T198340PX75pxBUSHFLOWJACKMINDVERY
-26T198430px75PXBINDGULFJACKVERSWHOM
-26T198430PX75pxBINDGULFJACKVERSWHOM

Honorable mention (132 bytes)

198640PX75pxBIRDFUCKGAVEHTMLJSON

[ai]

Can you update size-limit config to make PR diff?

[ai]

And can I ask you to add a note to the code about the reason behind this optimizaion?

[subzey]

The size-limit section is unchanged as the GZIPped sizes are the same.

This optimization only affects Brotli size that is currently not measured by size-limit (can it?)

[ai]

The size-limit section is unchanged as the GZIPped sizes are the same.

Oops. In this case we need only explanation comments.

This optimization only affects Brotli size that is currently not measured by size-limit (can it?)

It can with brotli config option. We can add extra Size Limit field for it.

[subzey]

I've force-pushed two commits:

8140bc8 Start measuring brotli in size-limit
1fd06c2 The implementation and size-limit section diff

[ai]

I combined brotli metrics since it is non-main use case (yeap, it will not be too accurate combined)

[ai]

Thanks. Released in 3.1.30.

[subzey]

Agree, this config looks more than enough for a good-to-have feature. Thanks!