feat(Gnovm/std): `GasUsed` function for `std`

[thinhnx-var]

Contributors' checklist...

• [x] 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
• [x] No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• [x] Added references to related issues and PRs
• [x] Provided any useful hints for running manual tests
• [ ] Added new benchmarks to generated graphs, if any. More info here.

As discussion in #1998, We should have this gasUsed() std function with two potential use cases:

1. This can be helpful for benchmarking gno code -- users trying to figure out which parts of their code is consuming large amounts of gas
2. This can be used to measure performance of running a bit of code if someone would like to deploy a leetcode style realm that accepts interfaces with methods for solving a posed coding problem.

This PR defines a GasUsed() func and a defaultInvokeCost in gas (?) within std package, and whenever the GasUsed() is invoked, the GasMeter will consume this amount, returns the GasConsumedToLimit.

(?) What is a reasonable number for this amount? I just set it to 1000 (store.DefaultGasConfig().ReadCostFlat). TODO: Should we move the default cost config into store.DefaultGasConfig ?

[thinhnx-var]

@thehowl can you take a look on this. I really need your opinion.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 23.07692% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 49.93%. Comparing base (088eeca) to head (2af4c25).

Files	Patch %	Lines
gnovm/stdlibs/native.go	0.00%	10 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2149      +/-   ##
==========================================
- Coverage   49.93%   49.93%   -0.01%     
==========================================
  Files         576      577       +1     
  Lines       77828    77841      +13     
==========================================
+ Hits        38862    38868       +6     
- Misses      35840    35849       +9     
+ Partials     3126     3124       -2     

Flag	Coverage Δ
gnovm	44.96% <23.07%> (+<0.01%)	:arrow_up:

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[thehowl]

Apologies for the late review

[Kouteki]

Fixes #2467

[thinhnx-var]

Closed due to #2571