Refactor pulseq.jl into multiple files

src/sequence_io/pulseq.jl

src/sequence_io/pulseq_io/basic_parsers.jl

src/sequence_io/pulseq_io/components.jl

src/sequence_io/pulseq_io/parse_sections.jl

src/sequence_io/pulseq_io/parsers/adc.jl

src/sequence_io/pulseq_io/parsers/blocks.jl

src/sequence_io/pulseq_io/parsers/definitions.jl

src/sequence_io/pulseq_io/parsers/delays.jl

src/sequence_io/pulseq_io/parsers/extensions.jl

src/sequence_io/pulseq_io/parsers/gradients.jl

src/sequence_io/pulseq_io/parsers/parsers.jl

src/sequence_io/pulseq_io/parsers/rf.jl

src/sequence_io/pulseq_io/parsers/shapes.jl

src/sequence_io/pulseq_io/parsers/trapezoids.jl

src/sequence_io/pulseq_io/parsers/version.jl

src/sequence_io/pulseq_io/pulseq_io.jl

src/sequence_io/pulseq_io/sections_io.jl

src/sequence_io/pulseq_io/types.jl

src/sequence_io/sequence_io.jl