Show results from page 1 when performing a new search

[xxsimoxx]

As spotted on the forum when a text search is performed the page is not reset to 1.
This lead to a 400 error.

This PR also adds more informations to the error message.

Before:

• Select "Install CP Plugin" from "Plugin" menu
• Navigate to page 7
• Search for "Security"
• "No plugins found" error is shown among "Bad Request (400)" ❌
• Search for "Classic"
• Notice that the current page is now 7 of 7 ❌
• Search for "klsretmgmsrb"
• Notice that only "No plugins found" error is shown. ✅

Testing:

• Select "Install CP Plugin" from "Plugin" menu
• Navigate to page 7
• Search for "Security"
• Notice that the current page is now 1 of 4 ✅
• Move to page 2
• Search for "Securit"
• Notice that the current page is now 1 of 4 ✅
• Search for "klsretmgmsrb"
• Notice that only "No plugins found" error is shown. ✅

[ClassyBot]

This pull request has been mentioned on ClassicPress Forums. There might be relevant details there:

https://forums.classicpress.net/t/400-bad-request-when-searching-cp-directory-integration/6123/2

[KTS915]

Using version 1.1.2, it's all working fine for me as it is.

[xxsimoxx]

@KTS915 I haven't reproduced the issue as in the forum post, but the "before" checklist showed an edge-case bug.
Can you reproduce the bug using the steps reported above?

[KTS915]

I went through the above steps, and everything worked as in the "after" but I was using the "before"! 😉

[xxsimoxx]

@KTS915 Weird! I've reproduced the issue on 3 different sites. Please take a look at my last commit to check if it makes sense.
I've changed the input type to search and it shows the search string now.

[mattyrob]

Tested as per steps described, works well.