Incorporate ABNF "inherited" references

There are a number of ABNF definitions "inherited" from specific RFC(s). These definitions need to be incorporated/duplicated into CBS in some fashion.

References:

https://tools.ietf.org/html/rfc5234#appendix-B

DIGIT = %x30-39

https://tools.ietf.org/html/rfc3339#section-5.6

date-fullyear = 4DIGIT
date-month = 2DIGIT ; 01-12
date-mday = 2DIGIT ; 01-28, 01-29, 01-30, 01-31 based on
; month/year
time-hour = 2DIGIT ; 00-23
time-minute = 2DIGIT ; 00-59
time-second = 2DIGIT ; 00-58, 00-59, 00-60 based on leap second
; rules
time-secfrac = "." 1*DIGIT
time-numoffset = ("+" / "-") time-hour ":" time-minute
time-offset = "Z" / time-numoffset

partial-time = time-hour ":" time-minute ":" time-second
[time-secfrac]
full-date = date-fullyear "" date-month "" date-mday
full-time = partial-time time-offset

date-time = full-date "T" full-time

https://tools.ietf.org/html/rfc3629#section-4

UTF8-octets = *( UTF8-char )
UTF8-char = UTF8-1 / UTF8-2 / UTF8-3 / UTF8-4
UTF8-1 = %x00-7F ; NEED TO CHANGE THIS to 0x01-7F TO EXCLUDE NUL?
UTF8-2 = %xC2-DF UTF8-tail

UTF8-3 = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
%xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
%xF4 %x80-8F 2( UTF8-tail )
UTF8-tail = %x80-BF

https://tools.ietf.org/html/rfc3987#section-2.2

dec-octet = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255