Organise folder structure

Make the following changes:

[x] Re-name unpackaged folder to legacy
[x] Add mvesuvio to source
[x] Add tools folder and include Mial's calibration scripts in it
[x] Remove vesuvio_analysis layer
[x] Create new folder for bootstrap scripts (technically they should go into unpackaged because they are not being used as of now)
[x] Organise analysis scripts such that the analysis_functions.py and fit_in_yspace.py are easily identifiable as the two main routines
[x] Update pyproject.toml (to know where the code for mvesuvio lives)
[x] Rename analysis script to more appropriate names
[x] Add tests folder for system and unit tests for analysis and calibration

mantidproject / vesuvio