Bar-shaped resource meter attributes

[rsek]

migrates resource meter attributes on items and actors to a schema that FVTT can infer as bar attributes (in other words, they have value and max).

Notes

• removes the system.experience attribute, which doesn't appear to be referenced in our codebase, and is presumably redundant with the system.xp attribute
• momentum still has some getters on CharacterData that it uses instead of actually accessing the system.momentum.resetValue and system.momentum.max properties; these will be addressed in Implement impacts/debilities as ActiveEffects #770
• added stricter typings to the various chat alert handlers
• added a type augmentation to describe FVTT's Document._addDataFieldMigration static method
• adds global typings for the augmentations that FVTT provides on Math
• adds an ESLint rule that forbids using lodash clamp, because FVTT does the same thing with Math.clamped. note that this is only applied on files i was already touching to avoid changes to unrelated files