This commit introduces initial Mode and ModTime support
for single filesystem files and webfiles.

The ipfs add options --preserve-mode and --preserve-mtime are
used to store the original mode and last modified time of the
file being added, the options --mode, --mtime and --mtime-nsecs
are used to store custom values.

A custom value of 0 is a no-op.

The preserve flags and custom options are mutually exclusive,
if both are provided the custom options take precedence.

Majority of of the code was from #7754 written by kstuart

Replaces #7753

Closes #6920

probably safer to error here, than printing line - if command was
executed over http it might be printed on the server, or break cli tools
that expect specific stdout rather than this line

was missing executable flag, so was skipped on ci
this should re-enable it

this will show us what values are read by 'stat' and compared by 'test'
when run on CI (tests fail there, but pass locally, so we need more
verbose log to debug this)

#10478

mountdir was used for both in and out, this isolates things
to ensure we dont mix inputs with outputs

turns out some github workers run with umask 002
which changes the default mode of files created with 'touch'

https://github.com/orgs/community/discussions/40876
#10478

Previously it only worked for a single object or top-level directory. This was only for rpc, as used by ipget, as it was already working for normal ipfs get.

just setting expectations

this follows 'no surprises' rule.

if user provided --raw-leaves=true explicitly, means they care, and we error
to let them correct parameter manually

if user added file without raw-leaves flag, but we have cidv1 which
implies raw-leaves,  we assume user does not mind changing implicit
raw-leaves behavior

switching to version with fix from
ipfs/boxo#653 (comment)
and adding tests

commit after merging
ipfs/boxo#653