Allow retriggering the cms-bot job using new bot

[iarspider]

If <newbot></newbot> or <new-bot></new-bot> tag is present anywhere in issue body, switch to new bot version proposed in #2626

[cmsbuild]

A new Pull Request was created by @iarspider for branch master.

@akritkbehera, @cmsbuild, @iarspider, @raoatifshad, @smuzaffar can you please review it and eventually sign? Thanks.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.
cms-bot commands are listed here

[cmsbuild]

cms-bot internal usage

[smuzaffar]

@iarspider , this can go in ... right?

[cmsbuild]

A new Pull Request was created by @iarspider.

@akritkbehera, @iarspider, @raoatifshad, @smuzaffar can you please review it and eventually sign/assign? Thanks.
cms-bot commands are listed here

[iarspider]

@smuzaffar yes.

[smuzaffar]

+externals

lets get this in for testing some dummy PRs