feat(gnovm): add /debug command in REPL

[mvertes]

The REPL /debug command activates the gnovm debugger on the next evaluation, allowing interactive debugging of interactive sessions.

One interest of this feature is the capability to run the debugger at no other cost also from the Gno playground.

Contributors' checklist...

• [*] Added new tests, or not needed, or not feasible
• [*] Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• [*] Updated the official documentation or not needed
• [*] No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• [*] Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

Attention: Patch coverage is 21.73913% with 18 lines in your changes missing coverage. Please review.

Project coverage is 54.79%. Comparing base (10a6f7e) to head (8c85deb).
Report is 51 commits behind head on master.

Files	Patch %	Lines
gnovm/pkg/gnolang/debugger.go	38.46%	8 Missing ⚠️
gnovm/pkg/repl/repl.go	0.00%	7 Missing and 1 partial ⚠️
gnovm/cmd/gno/repl.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2567      +/-   ##
==========================================
+ Coverage   54.71%   54.79%   +0.08%     
==========================================
  Files         583      593      +10     
  Lines       78499    81308    +2809     
==========================================
+ Hits        42947    44552    +1605     
- Misses      32344    33344    +1000     
- Partials     3208     3412     +204     

Flag	Coverage Δ
contribs/gnodev	26.00% <ø> (+2.18%)	⬆️
contribs/gnofaucet	14.46% <ø> (ø)
contribs/gnokeykc	0.00% <ø> (ø)
contribs/gnomd	0.00% <ø> (ø)
gno.land	64.39% <ø> (+1.84%)	⬆️
gnovm	60.26% <21.73%> (+0.27%)	⬆️

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[deelawn]

Looks good and works well when I ran it 👍

[ajnavarro]

@mvertes LGTM!!!