Update changelog for v8

[Gudahtt]

Any changes that were development-focused, or that solely affected newly-introduced features, have been omitted.

A duplicate '7.0' title has also been removed. It was accidentally added in a merge conflict.

[metamaskbot]

Builds ready [5f0b8b9]

• builds: chrome, firefox, opera
• bundle viz: background, ui, inpage, contentscript, ui-libs, bg-libs, phishing-detect
• dep viz: background
• all artifacts

Page Load Metrics (672 ± 35 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	31	84	46	18	9
		domContentLoaded	413	786	670	73	35
		load	418	788	672	72	35
		domInteractive	412	785	669	73	35

[whymarrh]

We can add #8850 once that's merged

[whymarrh]

LGTM!

[metamaskbot]

Builds ready [14ded0f]

• builds: chrome, firefox, opera
• bundle viz: background, ui, inpage, contentscript, ui-libs, bg-libs, phishing-detect
• dep viz: background
• all artifacts

Page Load Metrics (1475 ± 71 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	NaN	NaN	NaN	NaN	NaN
		domContentLoaded	1205	1800	1470	148	71
		load	1214	1804	1475	149	71
		domInteractive	1205	1799	1470	148	71