feat: destructuring of structs and messages

[Gusarich]

Issue

Closes #298.

Checklist

• I have updated CHANGELOG.md
• I have documented my contribution in Tact Docs: https://github.com/tact-lang/tact-docs/pull/PR-NUMBER
• I have added tests to demonstrate the contribution is correctly implemented: this usually includes both positive and negative tests, showing the happy path(s) and featuring intentionally broken cases
• I have run all the tests locally and no test failure was reported
• I have run the linter, formatter and spellchecker
• I did not do unrelated and/or undiscussed refactorings

[anton-trunov]

See my comment for the grammar.ohm file

[Gusarich]

@jeshecdom @anton-trunov have a look at the reworked apporach please!

[anton-trunov]

@Gusarich There are some merge conflicts

[Gusarich]

@Gusarich There are some merge conflicts

Resolved them, trying to push but knip doesn't let me because for some reason it thinks that @types/jest is not used. What should I do?

[anton-trunov]

Resolved them, trying to push but knip doesn't let me because for some reason it thinks that @types/jest is not used. What should I do?

hmmm, this is weird, because I removed that from ignoreDependencies (see the getter method id pr) precisely because I was getting warnings that it is useless

can you try updating your knip installation locally?

[Gusarich]

can you try updating your knip installation locally?

yeah, just had to run yarn. didn't notice the change in package.json. have a look now

[anton-trunov]

I left a few comments and suggestions for the changes. Since this is a complex feature (yeah, codegen is quite simple, but the static semantics is a bit tricky), we need to test it more thoroughly, so let's add at least the following tests:

• positive interpreter (const-eval) tests (including various combinations of punned and mapped fields);
• negative interpreter tests;
• negative typechecker tests with the scoping rules violations, like let S {x: x, y: x} and shadowing of previously defined variables;
• negative typechecker tests with all the new error messages (that are non-ICE ones);
• pretty-printer tests;
• renamer tests;

[anton-trunov]

@jeshecdom Please have a look at the interpreter changes and suggest more positive and negative tests. And also, please help with the var-scoping and typechecking rules review

[anton-trunov]

1. Also, let's document this feature: look at how it's done in PR feat: specify method ID for getters #922 ("available since").

2. And let's add some more negative tests for the typechecker in this style: let S1 {x, y} = S2 {x: 42, y: 43}

[novusnota]

Also, let's document this feature: look at how it's done in PR #922 ("available since").

If needed, I can quickly help write the docs once all the other suggestions above are resolved :)

[Gusarich]

@anton-trunov @jeshecdom I think I've made all the changes you requested in the review. Please have a look!

Discovered and fixed a few small bugs while writing all these tests 👍

[jeshecdom]

LGTM, @anton-trunov

[Gusarich]

@anton-trunov resolved everything, have a look please!

[anton-trunov]

If needed, I can quickly help write the docs once all the other suggestions above are resolved :)

@novusnota your turn :)

[novusnota]

@anton-trunov on it!

UPD: #964