improved performance for selected records. Only select all records when checkbox for all records has been clicked

Sometimes this hook gets called with no contact id, e.g. from the ContactLayout extension

PROJ-2313 Provides ability to set the file name for the CSV export download, instead of using randomly generated file name

When using the CSV export, the web browser can cache the downloaded CSV file preventing new versions of the CSV to be downloaded. Fixes !107

_Overview_: Civi 5.41 began migrating the "custom search" layer to an extension
(`legacycustomsearches`).  `dataprocessor` uses the "custom search" layer in a way that
provokes a hard/ubiquitous error during upgrade.  This revision makes it more robust
against upgrade errors.

_Before_: `hook_config` unconditionally (*on all page-views*) loads
`CRM_DataprocessorSearch_Form_Search_Custom_DataprocessorSmartGroupIntegration` and calls
`redirectCustomSearchToDataProcessorSearch()`.

_After_: `hook_config` only calls `CRM_DataprocessorSearch_Form_Search_Custom_DataprocessorSmartGroupIntegration`
if it's needed.

_Comments_:

* The error arises from when autoloading the base-class `CRM_Contact_Form_Search_Custom_Base`. This class
  exists, but it won't be available until the upgrade is complete.
* Strictly speaking, the two conditionals (on `$currentUrl` and `ssID`) are sufficient. I threw in a
  third conditional (`class_exists()`) as an extra bit of paranoia.
* I did a light `r-run` to ensure that the upgrade process works with the patch. However, I did not
  test the redirect.
* We're planning to include a short-term work-around in 5.41.1. However, this work-around will go away
  soon (eg 5.42 or 5.43).

CIVICRM-1696 Adjust error message "Did you rename or deleted the data source" should be "Did you rename or delete the data source"

CIVICRM-1695 Data Processor, default delimiter for CSV export is semi-colon, not comma, as per definition: Comma Separated Values (CSV)