Moves the method for getting IPF Paths into Experiment info as a static
method, so it can be called internally and by Python APIs

Moves iterating through all directories where an IPF could be into the
method which looks this up. This means a caller can still pass a
directory hint, which we will look at first.

But afterwards we will iterate over instrument directories on their
behalf, avoiding them needing to do this

Giovanni Di Siena authored Mar 31, 2020 and Gigg, Martyn Anthony committed Apr 07, 2020

In places other substitutions have been made, e.g
Clang does not yet specialize std::shared_ptr for T[]. Vector
has been used instead. The operator[] methods were incorrectly
marked const but returning a non-const reference - this has been fixed.
Refs #25842

Runs clang-tidy pass by ref across the codebase to fix-up various
warnings we are seeing in cppcheck

Also updated class_maker.py

Fixes case sensitivity in LoadInstrument; if the filename had
_Definition that does not follow the aforementioned case it would
instead embed the entire filename as the instrument. This was noticed in
the SANS workflow where they were fitting custom IDFs but other users
may have run into this.

- changed the directory search for instruments back to only searching inside `getInstrumentDirectories()`
- created a new `FileDescriptor` function `isXML()` to determine if a file is of XML type (currently this is true if the file is Ascii and has an ".xml" extension)
- made `FileDescriptor.extension()` to always be lowercase
- created new functions `toLower()` and `toUpper()` in `Kernel::Strings` to convert input strings to lowercase/uppercase
- added a test for `LoadEmptyInstrument` where `LOKI` is loaded from instrument name

Missing argument for function checkAndRetrieveInstrumentFilename()

Update copyright headers in all files

Squashed commit of the following:

* First version of a script to manage copyright statements

re #23468

* Neatened up script, added comments

re #23488

* move script to tools directory

re #23488

* small script changes and a couple of manual file changes

re #23488

* Minor chnage to whitespace detection in regex

re #23488

* Add an excluded directory

re #23488

* remove a repeasted copyright statement in a file

re #23488

* Don't comsume the comment end if it is on the same line

re #23488

* fix error in new copright parsing

re #23488

* remove double copyrifght entry

re #23488

* Improve handling of old copyrights at the start of comments

re #23488

* remove empty comments re #23488

* exclude gsoapgenerated directories

re #23488

* Sort out greedy line matching re #23488

* improve empty comment removal

re #23488

* improve false positives

re #23488

* impressive speedup by limiting regex matching length

re #23488

* remove evil invisible non ascii character

Also upadte the copyright at the same time

re #23488

* resolve multiple copyrights in a single file

re #23488

* resolve an issue with new statement detection

re #23488

* another unprintable unicode character

re #23488

* pep updates and cmake the new copyright fit clang format

re #23488

* update already done new format headers

re #23488

* wrong type of bracket

re #23488

* Update class_maker and friends

re #23488

* Update all copyright statements

re #23488

* clang format re #23488

* flake8 warnings re #23488

* Flake8 warnings re #23488

* Exclude .cmake.in and rb.in files

re #23488

* replace missing line re #23488

* exclude .py.in files as they are flasely recognized as C++

re #23488

* another setp.py.in re #23488

* another .py.in correction re #23488

* Hopefully the last of the .py.in files re #23488

* resolve utf-8 encoding of python files and changed ABINS checksum

re #23488

* updates to unit tests that reference line numbers

re #23488

* remaining unit test files and other fixes

re #23488

Update to clang-format-5 and reformat the codebase 

# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
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# Lines starting with '#' will be ignored, and an empty message aborts
# the commit.

This uses the -fix option on clang-tidy to automatically fix all
the unused usings declarations that have crept into Mantid.

Re #19071