feat: add eBird social icon svg

[liamacox]

What does this PR change? What problem does it solve?

Adds an eBird social icon based on https://commons.wikimedia.org/wiki/File:EBird_logo_full_white.svg. The wikipedia page claims the logo is in the public domain and that the creator "grants anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law." I have modified the original svg by removing the letters other than the e to better match the style of other social icons in the PaperMod theme.

I have no experience with making svg images so if anyone would like to make any improvements please go ahead!

Was the change discussed in an issue or in the Discussions before?

Closes #1847

PR Checklist

• This change adds/updates translations and I have used the template present here.
• I have enabled maintainer edits for this PR.
• I have verified that the code works as described/as intended.
• This change adds a Social Icon which has a permissive license to use it.
• This change does not include any CDN resources/links.
• This change does not include any unrelated scripts such as bash and python scripts.
• This change updates the overridden internal templates from HUGO's repository.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud