avoid bad url forging when contact logo from existing org

[cmangeat]

observed:
When displaying simple view, a bad url if forged (which can lead to session revocation at spring security level when anonymous).

-> Have indeed to use ng-attr-xlink:href or ng-attr-href so to allow expression evalution in angular template for xlink:href.

So to have the logo correctly displayed:
-> If 'link' test for '../api/logos', have to href '../api/logos', not '../../images/harvesting'.

when logo available

when logo not available

Checklist

• I have read the contribution guidelines
• Good housekeeping of code, cleaning up comments, tests, and documentation
• Clean commit history broken into understandable chucks, avoiding big commits with hundreds of files, cautious of reformatting and whitespace changes
• Clean commit messages, longer verbose messages are encouraged

[jahow]

Please do not use backticks (`) as they are part of ES5 and as such not compatible with the JavaScript tooling in GeoNetwork, thanks!

[cmangeat]

Please do not use backticks (`) as they are part of ES5 and as such not compatible with the JavaScript tooling in GeoNetwork, thanks!

done, thanks.

[jahow]

Looking good, just made a suggestion to simplify the code. Thanks!