Update severity for i18n codes

[ernilambar]

Regarding i18n improvement for the plugins, PRT team has decided to raise some WordPress.WP.I18n error codes to severity 7 making those blockers in the WP.org. As first step, following codes are made severity 7. These are pretty robust checks and irrespective of plugin text domain.

• WordPress.WP.I18n.InterpolatedVariableDomain
• WordPress.WP.I18n.MissingArgText
• WordPress.WP.I18n.NoEmptyStrings
• WordPress.WP.I18n.NonSingularStringLiteralContext
• WordPress.WP.I18n.NonSingularStringLiteralDomain
• WordPress.WP.I18n.TooManyFunctionArgs

Feature test scenario has also been added for new severity level.

Example errors which will be triggered as blockers:

      esc_html_e( 'Hello world', "${var}" );
      esc_html_e( domain: 'foo-sample' );
      esc_html_e( '%s', 'foo-sample' );
      echo esc_html_x( 'Hello world', $var, 'foo-sample' );
      esc_html_e( 'Hello world', $var );
      esc_html_e( 'Hello world', 'foo-sample', 'too-many-args' );

[github-actions]

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Co-authored-by: ernilambar <rabmalin@git.wordpress.org>
Co-authored-by: davidperezgar <davidperez@git.wordpress.org>
Co-authored-by: frantorres <frantorres@git.wordpress.org>

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