fix(strictest)!: don't implicitly allow js in strictest config

[manbearwiz]

This pull request removes checkJs from the strictest configuration.

The strictest config currently enables checkJs. Since TypeScript 4.1, when allowJs is not explicitly defined, its value is inferred from checkJs. This results in strictest implicitly setting allowJs: true, which can lead to unexpected behavior and conflicts with other compiler options.

For example, using strictest with isolatedDeclarations: true causes the following error because allowJs and isolatedDeclarations cannot be used together:

Option 'allowJs' cannot be specified with option 'isolatedDeclarations'.

This change removes checkJs from the strictest configuration to prevent allowJs from being enabled by default.

For reference, here's the code

    allowJs: {
        dependencies: ["checkJs"],
        computeValue: compilerOptions => {
            return compilerOptions.allowJs === undefined ? !!compilerOptions.checkJs : compilerOptions.allowJs;
        },
    },

[jakebailey]

Why not just set allowJs explicitly false here? Then, downstream users can turn it on as though the default were false.

[manbearwiz]

TS doesn't allow that

 Option 'checkJs' cannot be specified without specifying option 'allowJs'.

[orta]

This seems 👍🏻 to me