Clean-up contribution guidelines, dependencies, Test262, MSRV

[Razican]

Multiple small changes in this PR:

• Updates all dependencies in Rust and Yarn, also cleans-up the test_ignore.txt file a bit, where we had legacy comments.
• It uses the new flag in Cargo 1.56 to indicate that the minimum supported Rust version is, in fact, 1.56, which should help some compatibility diagnostics.
• Updates the Test262 sub-module with the latest changes to the official test-suite.
• It adds a clarification in the contribution guidelines to make users of the Boa tester know that they can get more complete output by using the "very, very, verbose" output mode.
• It fixes a small documentation warning.

[github-actions]

Test262 conformance changes:

Test result	main count	PR count	difference
Total	86,438	86,464	+26
Passed	38,514	38,500	-14
Ignored	19,055	19,061	+6
Failed	28,869	28,903	+34
Panics	0	0	0
Conformance	44.56%	44.53%	-0.03%

Broken tests (14):

test/built-ins/Reflect/getOwnPropertyDescriptor/return-from-data-descriptor.js [strict mode] (previously Passed)
test/built-ins/Reflect/getOwnPropertyDescriptor/return-from-data-descriptor.js (previously Passed)
test/built-ins/Reflect/getOwnPropertyDescriptor/symbol-property.js [strict mode] (previously Passed)
test/built-ins/Reflect/getOwnPropertyDescriptor/symbol-property.js (previously Passed)
test/built-ins/Reflect/getOwnPropertyDescriptor/return-from-accessor-descriptor.js [strict mode] (previously Passed)
test/built-ins/Reflect/getOwnPropertyDescriptor/return-from-accessor-descriptor.js (previously Passed)
test/built-ins/RegExp/named-groups/unicode-match.js [strict mode] (previously Passed)
test/built-ins/RegExp/named-groups/unicode-match.js (previously Passed)
test/language/computed-property-names/object/method/symbol.js [strict mode] (previously Passed)
test/language/computed-property-names/object/method/symbol.js (previously Passed)
test/language/computed-property-names/basics/symbol.js [strict mode] (previously Passed)
test/language/computed-property-names/basics/symbol.js (previously Passed)
test/language/expressions/object/cpn-obj-lit-computed-property-name-from-yield-expression.js [strict mode] (previously Passed)
test/language/expressions/object/cpn-obj-lit-computed-property-name-from-yield-expression.js (previously Passed)

[RageKnify]

LGTM, a bit concerned with the tests that stopped passing

[RageKnify]

Looked into the failing tests, think I know what's wrong, here's the code of one of them:

var o1 = {
  p: 'foo'
};

var result = Reflect.getOwnPropertyDescriptor(o1, 'p');

assert.compareArray(
  Object.getOwnPropertyNames(result),
  ['value', 'writable', 'enumerable', 'configurable']
);
assert.sameValue(result.value, 'foo');
assert.sameValue(result.enumerable, true);
assert.sameValue(result.configurable, true);
assert.sameValue(result.writable, true);

After some debugging the problem seems to be that result gets overwritten after being assigned (changing var result to const result results in "TypeError": "Cannot mutate an immutable binding result"), I assume it is related to scoping, inside assert.compareArray there is also a var result that I'm guessing overwrites the previous value.

Maybe a problem with how vars are scoped in functions? Scoping is one area I'm not very familiar with so there might be someone better suited to fix this.

[raskad]

Yes this is definitely a scoping error. This issue describes the same error: #1663

[RageKnify]

Yes this is definitely a scoping error. This issue describes the same error: #1663

Ok, I did think I'd seen it mentioned already, if we have an issue for it then I guess we can ignore the regression and let this PR through.