PDG: Unify masses in PhysicsConstants.h and O2DatabasePDG

[vkucera]

Declares additional enum values for particle PDG codes and defines mass constants for them + those in PDG_t.

This is one of the last steps of unifying the mass constants in O2 and O2Physics. (See AliceO2Group/O2Physics#2178) @ddobrigk@mpuccio

This moves the content of PDG.h (introduced in AliceO2Group/O2Physics#3115) into CommonConstants/PhysicsConstants.h and adds a Python script for generating it from O2DatabasePDG.

Context

Current situation

• Masses in PhysicsConstants.h are different from the ones provided by the O2DatabasePDG service.
• O2P/PWGHF/Core/PDG.h + the update script provides constants and PDG enums for particles used in the analyses, which have names consistent with the naming scheme in ROOT/PDG_t and mass values equal to those in O2DatabasePDG.
• We need the enums, the constants and the service and we need to keep them synced.

Result

• All needed PDG masses are accessible from a single location: PhysicsConstants.h in a single namespace: o2::constants::physics.
• Code using constants currently defined in PhysicsConstants.h does not need to be changed thanks to the aliases.
• Mass values in headers (taken from o2::constants::physics) are equal to what one gets from the O2DatabasePDG service in the tasks.
• Mass values can be synced with O2DatabasePDG by using a Python script which generates the body of the new block in PhysicsConstants.h. -> If masses change, someone knows about it and can update the header and inform the community.

Caveats

• Change from float to double to guarantee equivalence with O2DatabasePDG.
• Some masses change their values with this PR (see the table below) and will change them again with future ROOT upgrades and O2DatabasePDG modifications. (See Update script for PDG table root-project/root#13354)
• This PR reverts the update of masses for XiCCPlusPlus and OmegaC0 previously done in RecoDecay (see the table below).

Mass comparison

Particle	PDG code	PhysicsConstants	RecoDecay	O2DatabasePDG	ROOT/v6-29-02
Photon	22	0	O2DatabasePDG	0	0
Electron	11	0.000511	O2DatabasePDG	0.00051099891	0.0005109990
Muon	13	0.105658	O2DatabasePDG	0.105658	0.1056584
PionCharged	211	0.13957	O2DatabasePDG	0.13957	0.1395704
PionNeutral	111	0.134976	O2DatabasePDG	0.134977	0.1349768
KaonCharged	321	0.493677	O2DatabasePDG	0.493677	0.4936770
KaonNeutral	311	0.497648	O2DatabasePDG	0.497614	0.4976110
Proton	2212	0.938272	O2DatabasePDG	0.938272	0.9382721
Lambda	3122	1.115683	O2DatabasePDG	1.11568	1.115683
Deuteron	1000010020	1.8756129	O2DatabasePDG	1.87561294257	x
Triton	1000010030	2.8089211	O2DatabasePDG	2.80892113298	x
Helium3	1000020030	2.8083916	O2DatabasePDG	2.80839160743	x
Alpha	1000020040	3.7273794	O2DatabasePDG	3.7273794066	x
HyperTriton	1010010030	2.992	O2DatabasePDG	2.99131	x
Hyperhydrog4	1010010040	3.931	O2DatabasePDG	3.9226	x
Hyperhelium4	1010020040	3.9218	O2DatabasePDG	3.9217	x
XiMinus	3312	1.32171	O2DatabasePDG	1.32171	1.321710
OmegaMinus	3334	1.67245	O2DatabasePDG	1.67245	1.672450
XiCCPlusPlus	4422	x	3.62155	3.59798	3.62155
OmegaC0	4332	x	2.69520	2.6975	2.695200