Update intersphinx links and others

[woodsp-ibm]

Summary

Updates links away from qiskit.org to the new locations for the docs

Fixes #1304 Fixes #1305

Details and comments

Now that all the applications and the algorithms docs are deployed on github pages this updates the intersphinx links, in conf.py, and also urls that are coded directly in other places such as the readme and tutorials. I did not alter past release notes. There is a redirect now in effect for the former location on qiskit.org/ecosystem so they get to the right place.

Note that the current theme is still emitting a link to qiskit.org/ecosystem, but that will get redirected for now until such time as Qiskit/qiskit_sphinx_theme#588 is resolved and new docs are generated with such an updated theme and re-deployed.

[coveralls]

Pull Request Test Coverage Report for Build 7729107195

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 86.765%

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Totals
Change from base Build 7657109851:	0.0%
Covered Lines:	8785
Relevant Lines:	10125

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💛 - Coveralls