Loosen @typescript-eslint/naming-convention to allow properties with custom-element-names

[jattasNI]

Justification

Fixes #111.

Implementation

Based off the third example in the rule's documentation under Ignore properties that require quotes, I am using a regex to match properties that follow the lower-hyphen-case naming convention of custom elements, and turning off format checks for properties that match.

Testing

Locally tried these cases with the results described in the comments.

declare global {
    interface HTMLElementTagNameMap {
        'valid-custom-element': NI; // passes because of new configuration
        'valid-custom-element2': NI; // passes because of new configuration
        '2invalid-custom-element': NI; // fails because custom-element regex requires starting with a-z

        'nohyphen': NI; // passes because camelCase (with no capitals) is allowed by original configuration
        'noHyphen': NI; // passes because camelCase is allowed by original configuration
        camelCase: NI; // passes because camelCase is allowed by original configuration

        'Capital-Custom-Element': NI; // fails because PascalCase is disallowed by original configuration and new regex only matches lower case
        'capital-Custom-Element': NI; // fails because PascalCase is disallowed by original configuration and new regex only matches lower case
        PascalCase: NI; // fails because PascalCase is disallowed by original configuration
    }
}

Also did some testing in nimble and SystemLinkShared with locally built packages. This allows us to get rid of a global suppression in nimble and only add one inline suppression. It doesn't really help with SystemLinkShared because the one place that uses this pattern is an older library that has a custom naming-convention configuration so the one from the styleguide doesn't apply. However we should be able to copy the same pattern from this PR into that custom configuration.