refactor(core): apply numerated to pages

[grishasobol]

Fixes #3830
Related PR: #3791

Make pages refactoring:

1. Split pages implementation for gear-core and gear-lazy-pages to increase safety.
2. Append Numerated implementation for gear and wasm pages in gear-code and gear-lazy-pages.
3. Now WasmPage and GearPage are just type names over Page<SIZE>.
4. Append new struct PagesAmount<SIZE>, which should be considered as possible wasm or gear pages amount. In comparison PagesAmount<SIZE> max value is bigger than Page<SIZE> max value, because indexes amount is always bigger than max possible index, if indexes start from 0.
5. Alloc algorithm is slightly changed in order to suit for new pages implementation.
6. Append lots of tests for pages.

Apply IntervalsTree for gear-lazy-pages in order to simplify work with sets of pages and show how to work with tree.
NOTE: IntervalsTree is NOT applied to gear-core in order to split big changes in code in one PR: migration, benchmarks changes and changes in runtime code.

[breathx]

So huge refactoring
But in the end most parts of the code looks much better. GJ!

[breathx]

I guess it won't be excess to check this PR on validators so we're 100% sure that no compatibility broken and nothing is differ from current impl

[breathx]

@ark0f please review

[grishasobol]

I guess it won't be excess to check this PR on validators so we're 100% sure that no compatibility broken and nothing is differ from current impl

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