feat(gnovm/std): Add Alloc Usage features to std

[thinhnx-var]

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.

As mentioned in #2070, because it's possible to pull various things from MachineState, this PR will:

1. Expose functions to get Allocator Status from the contracts.
2. Contract developers can create an AllocTracker to monitor memory allocation. This tracker utilizes the Allocator.Status() function and leverages the Register() and Finish() functions defined within the AllocTracker interface. Additionally, I've exposed a GetResult() function that internally calls Finish() and returns the resulting Allocated Usage information.

Simple contract example:

func DemoGetUsage() int64 {
	a := std.CreateATInstance()
	des := "test description"
	a.Register(des)

	// --- Do some stuffs ---

	a.Finish()
	return a.GetAllocUsage()
}

func DemoGetUsage2() int64 {
	a := std.CreateATInstance()
	des := "test description"
	a.Register(des)

	// --- Do some stuffs ---

	return a.GetResult()
}

I will update examples for this later if this PR is good enough to go.

I propose moving both std.GasUsed() (introduced in issue #1998 and implemented in pull request #2148) and this new function, std.AllocatedMem(), to the runtime package. This would facilitate the development of PProf-like profiling tools within Gno. I'll provide a more detailed proposal soon with the specific implementation details.

[thinhnx-var]

@thehowl
I'd appreciate your feedback on this pull request at your earliest convenience.

[moul]

I would recommend:

• Not adding the new helpers and instead focusing on adding ways to measure performance without requiring userland solutions, such as using gno test -cover, gno test -profile, or a debugger.
• Alternatively, adding the new helpers but only for unit tests, such as std.TestXXX....

The advantages of exposing these helpers for non-test runtime are not immediately clear.

[thinhnx-var]

@moul
I am thinking about gno test -profile. I will push a proposal for discussing about the output more to make it clearer.

[thinhnx-var]

related proposal here #2222

[thinhnx-var]

Closed due to adding -print-runtime-metrics flag.