modules/dbe - lz4 encoder and decoder [DSLX code only]

[rdob-ant]

This is an implementation of Lz4 encoder and decoder in DSLX without reference Python & cocotb test code that was present in #1079.

The source branch additionally includes changes from #1078 that are needed to run DSLX tests of procs using 1R1W single-partition RAM. These will be dropped by rebasing when we get that PR merged.

[tmichalak]

CC @proppy @hongted

[proppy]

xls/examples/ram.x

Looks like there is a conflict, can we rebase?

[rdob-ant]

@proppy will rebase when pushing updated code

[proppy]

Should we close this in favor of the work on #1211 ?

[proppy]

@tmichalak closing this now that the more relevant #1315 has been merged.