added default params to theme providers

src/mol-plugin/behavior/dynamic/custom-props.ts

src/mol-plugin/state/transforms/representation.ts

src/mol-theme/color.ts

src/mol-theme/color/carbohydrate-symbol.ts

src/mol-theme/color/chain-id.ts

src/mol-theme/color/cross-link.ts

src/mol-theme/color/element-index.ts

src/mol-theme/color/element-symbol.ts

src/mol-theme/color/molecule-type.ts

src/mol-theme/color/polymer-id.ts

src/mol-theme/color/polymer-index.ts

src/mol-theme/color/residue-name.ts

src/mol-theme/color/secondary-structure.ts

src/mol-theme/color/sequence-id.ts

src/mol-theme/color/shape-group.ts

src/mol-theme/color/uniform.ts

src/mol-theme/color/unit-index.ts

src/mol-theme/size.ts

src/mol-theme/size/physical.ts

src/mol-theme/size/uniform.ts