[demo] URLSearchParams function in JavaScript

YSH has a good core!  I was able to do it in pure YSH, and Eggex has a
good structure.

But it needs polish!  See comments at the top of the file.

[mycpp] Add assign/define annotations to control flow graph (#2022)

[osh breaking] read -0 myvar has an implicit IFS=

That is, it doesn't respect the shell quirk of these two things being
different with respect to whitespace:

    read        # $REPLY
    read myvar

I noticed this due to the bug report about IFS= read -r, which also led
to read --raw-line

[mycpp] share if-statement special cases with all visitors (#2021)

fix spec tests

[ysh breaking] module builtin renamed to source-guard

Because we will likely have Python-like module with 'use'.

[ysh] Use more consistent syntax for loop over stdin

    for x in (stdin) {
      echo $x
    }

not

    for x in <> {
      echo $x
    }

This was a pretty simple change - just add value.Stdin.

The <> syntax is now reserved.  We could maybe use it for a "magic"
awk-like loop.

[refactor] Migrate more of our own scripts to OSH stdlib

[stdlib] yblocks polish, Add LIB_YSH

I realized we don't need yb-run or yb-redir.  We can just use the 'try'
builtin, which is nice.

In OSH, we need nq-run and nq-redir, nq-redir-2, because we don't have
try

[stdlib] Use 'module' include guard for two.sh

Rename to yb-capture, etc.

[rename] To yblocks.ysh and devtools/byo.sh

[stdlib/ysh] Got nq-capture working in YSH!

with value.Place style, and blocks.

[stdlib/ysh] Start porting no-quotes.sh to see how it works

How about:

    nq-capture-2 (&r) {
      log hi
    }
    assert [0 === r.status]
    assert ['hi' === r.stderr]

Switch to gawk for printing functions, because OSH/YSH don't have shopt
-s extdebug behavior.

[stdlib] Implement nq-redir, nq-redir-2, with tests

Add a new test file.

[devtools/xshar] Fix manifest for test-oils.xshar

Really need osh-tool deps

[stdlib/osh] task-five automatically makes the script a BYO server

Also plan out flag parsing for

    byo-client run-testes

Probably should be 'byo test'

[stdlib/osh] Add nq-run for getting status only

This is necessary so set -o errexit doesn't abort the shell!

Use it in benchmarks/time-test.sh

[test refactor] Start using $LIB_OSH

Some trivial cahnges

- assert -> nq-assert
- Use bash-strict.sh, etc.

[stdlib, byo] Small tweaks to use it in the blog-code repo

Using it for "catbrain".

[doc] Examples for stream-table-process

[doc] Link to 3 new docs

- BYO is incomplete, but ready to read
- lib-osh and stream-table-process are drafts, not ready to read