Autocomplete: Add MoreItemsTemplate RenderFragment.

[Mr-Technician]

Description

This PR adds a <MoreItemsTemplate> render fragment to the autocomplete. The component has a means of limiting the items displayed but provides no indication to the user that the list of items may be truncated. This PR provides a means of displaying a render fragment in the number of items returned from the SearchFunc is greater than the MaxItems count.

For example:

<MudAutocomplete T="string" Label="US States" @bind-Value="value1" SearchFunc="@Search1"
ResetValueOnEmptyText="@resetValueOnEmptyText"
CoerceText="@coerceText" CoerceValue="@coerceValue" MaxItems="10">
    <MoreItemsTemplate>
        <MudText Align="Align.Center">
        Not all items are shown.
        </MudText>
    </MoreItemsTemplate>
</MudAutocomplete>

My biggest caveat is the items IEnumerable must be enumerated twice, once to get the count of items, and once to take the appropriate number according to MaxItems. There may be a way to better optimize this (I don't care how long the items IEnumberable is, provided it is longer than MaxItems).

How Has This Been Tested?

I have added a unit test

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• The PR is submitted to the correct branch (dev).
• My code follows the code style of this project.
• I've added relevant tests.

[Mr-Technician]

@Garderoben I believe this is in your area.

[Mr-Technician]

Actually @henon this might be more for you, what do you think of this change?

[henon]

I approve of this addition. Could be used to implement a "Show more" or "Show all" functionality.

[Mr-Technician]

@henon I've made the change you requested. Should this feature have its own docs section or is its presence under the API enough?

[codecov]

Codecov Report

Merging #4566 (c62a453) into dev (e8536f8) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev    #4566      +/-   ##
==========================================
+ Coverage   91.27%   91.30%   +0.03%     
==========================================
  Files         362      362              
  Lines       12481    12502      +21     
==========================================
+ Hits        11392    11415      +23     
+ Misses       1089     1087       -2     

Impacted Files	Coverage Δ
...azor/Components/Autocomplete/MudAutocomplete.razor	94.44% <100.00%> (+0.69%)	⬆️
...r/Components/Autocomplete/MudAutocomplete.razor.cs	94.25% <100.00%> (+0.05%)	⬆️
...azor/Services/ResizeListener/BreakpointService .cs	93.02% <0.00%> (-0.09%)	⬇️
...azor/Components/DatePicker/MudBaseDatePicker.razor	97.72% <0.00%> (-0.06%)	⬇️
src/MudBlazor/Components/Input/MudInput.razor	100.00% <0.00%> (ø)
.../MudBlazor/Components/TextField/MudTextField.razor	100.00% <0.00%> (ø)
src/MudBlazor/Components/Select/MudSelect.razor.cs	96.75% <0.00%> (+0.03%)	⬆️
src/MudBlazor/Base/MudFormComponent.cs	87.98% <0.00%> (+0.05%)	⬆️
...azor/Components/DropZone/MudDropContainer.razor.cs	97.50% <0.00%> (+0.06%)	⬆️
... and 6 more

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[Yomodo]

@henon I've made the change you requested. Should this feature have its own docs section or is its presence under the API enough?

I believe this nifty feature deserves its own docs section.

[henon]

You are right of course. I overlooked that question from @Mr-Technician, sorry.

[Mr-Technician]

I can add a docs section this evening (or at some point in the next few days at least) but I'll make a new PR since this one is already merged.