Simplifying `pyrightconfig.*.json`

[Avasam]

I'm just wondering if there's any reason to not use "typeCheckingMode": "strict" ?
The configs could be simplified to:

    [...]
    "typeCheckingMode": "strict",
    "reportPrivateUsage": "none",
    "reportIncompleteStub": "none",
    "reportMissingModuleSource": "none",
    // Incompatible overrides and property type mismatches are out of typeshed's control
    // as they are inherited from the implementation.
    "reportIncompatibleMethodOverride": "none",
    "reportIncompatibleVariableOverride": "none",
    "reportPropertyTypeMismatch": "none",
    // Overlapping overloads are often necessary in a stub, meaning pyright's check
    // (which is stricter than mypy's; see mypy issue #10143 and #10157)
    // would cause many false positives and catch few bugs.
    "reportOverlappingOverload": "none",
    // The name of the self/cls parameter is out of typeshed's control.
    "reportSelfClsParameterName": "none",

Similarly pyright.testcases.json can be simplified to:

    [...]
    "typeCheckingMode": "strict",
    "reportPropertyTypeMismatch": "error",
    "reportUnnecessaryTypeIgnoreComment": "error",
    "reportMissingModuleSource": "none",
    "reportPrivateUsage": "none",

[AlexWaygood]

I'm just wondering if there's any reason

Probably just because most of the typeshed core devs are more familiar with mypy than pyright; it hasn't broken anything being that way; and it's always been like that :)

It can probably be simplified! I'll happily review a PR.