ENH+NF: add javascript customization options via config

[jsheunis]

This PR:

• Addresses: ENH: decrease prominence of "Export metadata" button #281
• Addresses: ENH: ability to customize icon links at top right. #282

Both are done by allowing more configuration options via the config file, basically resulting in show/hide logic for certain UI components.

In order to apply these changes to an existing catalog, the affected html and javascript files will have to be checked out into the existing catalog repo, and the catalog's config file will need to be updated with the "social_links" and "dataset_options" fields.

Towards parts of sfb1451/metadata-catalog#5

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (377fffe) 82.67% compared to head (b009163) 82.67%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #283   +/-   ##
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  Coverage   82.67%   82.67%           
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  Files          32       32           
  Lines        2164     2164           
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  Hits         1789     1789           
  Misses        375      375           

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[mih]

I do not have efficient means to generate a test catalog to see the effects of the proposed changes, and there are no screenshots provided -- so my comments are superficial and from skimming the diff. LGTM.

[jsheunis]

Ooh sorry (it's about time to implement #273 then)

Here are some examples:

1

config: {
    ...
    "social_links": {
        "about": null,
        "documentation": null,
        "github": null,
        "twitter": null
    },
    "dataset_options": {
        "include_metadata_export": false
    },
    ...
}

2

config: {
    ...
    "social_links": {
        "about": null,
        "documentation": "https://docs.datalad.org/projects/catalog/en/latest/",
        "github": "https://github.com/datalad/datalad-catalog",
        "twitter": "https://twitter.com/datalad"
    },
    "dataset_options": {
        "include_metadata_export": true
    },
    ...
}

[jsheunis]

Ok, fire in the hole.