fixup! Adding issue and merge request templates

<!-- Bookkeeping information for release management -->

### Related Issues

### Issues

#### Resolves

- tor-browser#xxxxx

- mullvad-browser#xxxxx

- tor-browser-build#xxxxx

#### Related

- tor-browser#xxxxx

- mullvad-browser#xxxxx

- tor-browser-build#xxxxx

### Merging

<!-- This block tells the merger where commits need to be merged and future code archaeologists where commits were *supposed* to be merged -->

#### Target Branches

- [ ] **`tor-browser`** - `!fixups` to `tor-browser`-specific commits, new features, security backports

- [ ] **`base-browser`** *and* **`mullvad-browser`** - `!fixups` to `base-browser`-specific commits, new features to be shared with `mullvad-browser`, and security backports

  - ⚠️ **IMPORTANT**: Please list the `base-browser`-specific commits which need to be cherry-picked to the `base-browser` and `mullvad-browser` branches here

#### Target Channels

- [ ] **Alpha**: esr128-14.5

- [ ] **Stable**: esr128-14.0

- [ ] **Legacy**: esr115-13.5

### Backporting

#### Timeline

- [ ] **No Backport (preferred)**: patchset for the next major stable

- [ ] **Immediate**: patchset needed as soon as possible

- [ ] **Next Minor Stable Release**: patchset that needs to be verified in nightly before backport

- [ ] **Eventually**: patchset that needs to be verified in alpha before backport

- [ ] **No Backport (preferred)**: patchset for the next major stable

#### (Optional) Justification

- [ ] **Emergency security update**: patchset fixes CVEs, 0-days, etc

- [ ] **Localization**: typos and other localization changes that should be also in the release branch

- [ ] **Other**: please explain

### Merging

- [ ] Merge to `tor-browser` - `!fixups` to `tor-browser`-specific commits, new features, security backports

- [ ] Merge to `base-browser` - `!fixups` to `base-browser`-specific commits, new features to be shared with `mullvad-browser`, and security backports

  - **NOTE**: if your changeset includes patches to both `base-browser` and `tor-browser` please clearly label in the change description which commits should be cherry-picked to `base-browser` after merging

### Issue Tracking

- [ ] Link resolved issues with appropriate [Release Prep issue](https://gitlab.torproject.org/groups/tpo/applications/-/issues/?sort=updated_desc&state=opened&label_name%5B%5D=Release%20Prep&first_page_size=20) for changelog generation

#### Request Reviewer

- [ ] Request review from an applications developer depending on modified system:

  - **NOTE**: if the MR modifies multiple areas, please `/cc` all the relevant reviewers (since gitlab only allows 1 reviewer)

  - **NOTE**: if the MR modifies multiple areas, please `/cc` all the relevant reviewers (since Gitlab only allows 1 reviewer)

  - **accessibility** : henry

  - **android** : clairehurst, dan

  - **build system** : boklm

  - **firefox internals (XUL/JS/XPCOM)** : jwilde, ma1

  - **fonts** : pierov

  - **frontend (implementation)** : henry

  - **frontend (review)** : donuts, richard

  - **frontend (review)** : donuts, morgan

  - **localization** : henry, pierov

  - **macOS** : clairehurst, dan

  - **nightly builds** : boklm

  - **rebases/release-prep** : dan, ma1, pierov, richard

  - **rebases/release-prep** : dan, ma1, pierov, morgan

  - **security** : jwilde, ma1

  - **signing** : boklm, richard

  - **signing** : boklm, morgan

  - **updater** : pierov

  - **windows** : jwilde, richard

  - **misc/other** : pierov, richard

  - **windows** : jwilde, morgan

  - **misc/other** : pierov, morgan

#### Change Description

<!-- Whatever context the reviewer needs to effectively review the patchset; if the patch includes UX updates be sure to include screenshots/video of how any new behaviour -->

#### How Tested

<!-- Description of steps taken to verify the change -->