Fix skip to content link position

[DenisHdz]

Resolves #NUMBER

Overall change:
The skip to content link was in the wrong position on IE:

Code changes:

• Add top and left/right properties to the SkipLink
• Add Script link to the last story
• Export ScriptLink from a separated folder to reduce index length.

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• I have assigned myself to this PR and the corresponding issues
• Automated jest tests added (for new features) or updated (for existing features)
• This PR requires manual testing

[OlgaLyubin]

For rtl it seems like the text from the ScriptLink is overflowing the Skip to content

[DenisHdz]

@OlgaLyubin It would be solved adding z-index to the SkipLink, but we have decided to put it on the right side for rtl services, so it should be fine.

[OlgaLyubin]

Looks good on IE 👍

[j-pendlebury]

Looks good 👍

[jamesbrumpton]

lgtm