Deduplicate headers for overloaded methods

[arnaucasau]

Closes #167

The script was creating a title for every <dt> tag inside a <dl> tag. This is almost always correct given that we only have a <dt> tag for each method. The problem with overload methods is that we have a <dt> for each @typing.overload definition.

For example, the quantumcircuit.py file overloads the definition of for_loop:

https://github.com/Qiskit/qiskit/blob/244940a10c17f1dc3d74e2665a3ae869dc3d7291/qiskit/circuit/quantumcircuit.py#L4862-L4884

This is an example of the HTML generated

<dl class="py method">
    <dt class="sig sig-object py" id="qiskit.circuit.QuantumCircuit.for_loop">
    <span class="sig-name descname"><span class="pre">for_loop</span>

    <dt class="sig sig-object py">
    <span class="sig-name descname"><span class="pre">for_loop</span>
    
    <dd><p>Create a <code class="docutils literal notranslate"><span class="pre">for</span></code> loop on this circuit.</p>

To solve the problem this PR adds an extra condition to check whether the <dt> tag has an id or not. Only the first <dt> tag will have an id, so we can use this fact to create only one <h3> for each method.

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[Eric-Arellano]

Excellent! Great work. I like the solution.

Thoughts on adding a test for these? I know it's not super obvious how to do so because we punted on adding tests for processMembersAndSetMeta.

[arnaucasau]

I think it's a good idea to add tests. What do you think about adding them as a follow-up together with more cases for the processMembersAndSetMeta function? I'm going to test the generation with runtime and provider to make sure it doesn't break anything

[frankharkins]

Neat solution and nice comment, thanks!

EDIT: Approval for after resolving Eric's comments